i HAVOC mayhem
We let slip the dogs of with a nice simple inclusion: sucH A VOCal, a piece of which creates our answer.
4 CHOW MEIN dish
O my, another easy one. "My" in German with a CHOW dog put first. Cantonese for "secret weapon to make westerners despair of using chopsticks".
8 NEGATIVE EQUITY can prevent you moving..
...since your mortgage has been overtaken by your plummeting house value. Translation of no and justice.
10 SUETONIUS (old) historian
Gaius Suetonius Tranquillus wrote, inter alia, De Vita Caesarum, biographies of the first twelve Caesars. Our students are the National Union of Students, into which you insert a Latin one. Following instructions you place that that construct after SUET/fat and O(ld)
11 DONNE poet
A bell tolled the hastening seconds for me (I didn't ask) as I scratched around to work out how this could be Dante. Or Dunne. Or some other poet whose letters would fill the gaps. Only when I remembered the old legal maxim "de accentibus non curat tempora" did the penny drop. A DONNÉ is indeed a basic assumption. We'll take that as a given
12 BEWAIL Lament
A judge might grant BAIL to keep bridge partners East and West together. Though I wouldn't bother. East has never forgiven West for calling 3 no trumps when they were vulnerable.
14 REIGNING current
As in ...champion. in a supple, bendy way, the letters of ENGINE RIG missing one of the E(nergy)s provides our answer
17 OMISSION Failure
A new (I think) addition to spectacles for OO and suchlike. O resembles a bullet hole if the setter wants it to, and Davy, Davy Crockett's Alamo was a MISSION station before it became the legendary failed defence and/or care hire company.
18 SATNAV travel guide
I was struggling to remember those weird words like dragoman and had to do a U turn where possible in order to reach my destination. The day is SAT, and sailors NAVy minus ¥
20 EWERS spouted things
Commonly pronounced HEWERS of wood would lose their aitch.
22 STREETCAR Desire for one (example)
Best of the bunch for me, not least because the large plant even I have heard of, because it's just a TREE. Back of cleft is T: pair those two and insert into SCAR for cliff.
A cryptic definition in which you have to untangle the inherent negatives
25 UGLINESS nothing attractive...
...unless you have a taste for 60's concrete brutalism, of course. America gives US, insert G(ood) LINES for "routes"
26 TINGE Slight colouring
You have to work hard to split the segments properly. "For one" provides E.G. and "egg" NIT. Assemble and reverse.
1 HONEST BROKER Mediator
Really translates to HONEST with a bit of license, and BROKE for damaged needs the R from the back end of affair.
2 VOGUE popularity
Once you realise that I is in Latin, and remember EGO, V is also Latin for see, as in V(ide), all you have to do is chuck in a U(niversity) and reverse the lot
A rather neat &lit in which the (rather full) heart of s(CHOLASTIC)s is trained to produce the "members of the fastest growing religion in the world, my boy."
4 CAVE IN abandon resistance
If everyone deserts Call, you are left with the C. Add A VEIN, which is a (blood) vessel.
5 OLEASTER tree
The wild olive, so I'm informed. There isn't a festival called EANDER, so settle for the one that, after LO(ok) "up" produces the tree.
6 MOULD fungus
...or indeed form (verb)
7 INTENTION Meaning
Does sound remakably like "in tension", under strain
9 TERGIVERSATE change sides
Give a new order to REVISE TARGET. I think there's only one way to fill the checkers, but this is a monstrous, pretentious concoction which, for all its usefullness to describe what politicians do, should really be laid to rest. Bleh!
13 WHITE FLAG signal to enemy
The anagram indicator is "flares", and the raw material LIGHT A FEW
15 GRAPESHOT Ammunition
Looks horrified: GAPES, R(esistance) and burning: HOT. Assemble for primitive shrapnel
16 NOISETTE A little lamb
The top dog might well be the No 1 SETTER. Take the finish off
19 TROOPS Soldiers
R(un) O(ver) is contained withing TOPS, which is what singlets can be.
21 SAUDI Arab
A small sound systtem would be a S AUDIO. omit 0 (nothing)
23 CABIN compartment
CAIN is your murderer, his victim Abel. The first of Blood provides the "concealed" B.