I'd wondered whether the Jumbo for the weekend between Christmas and New Year would be tougher than uual, as a holiday bonus, but that didn't seem to be the case; I managed to time myself properly for this one, and it took me 20 minutes (and 8 seconds).

As ever, * indicates an anagram.

Across
1	CHUFFED - C + HUFFED (reference to the wolf who "huffed and puffed" and blew the little pigs' house down)
5	FAIL-SAFE - F + AIL, + (A + S) reversed, + FE (chemical symbol for iron)
9	HINGES - NG + E in HIS
13	RETURNING OFFICER - double definition
14	OCULAR - jOCULAR
16	NEW STYLE - refers to the "New Style" calendar introduced in 1752
17	ARCH - hidden in cAR CHase
18	APOLOGISE - A POISE around LOG
20	PASADENA - SAD ENA after PA (defined by "old man" = father)
21	REENACTMENT - (recent)* around A, + MEaNT
24	PRESENTER - PRESENT + ER. Here, "anchor" indicates a TV anchorman/anchorwoman
25	IDENTITY - Y (symbol for an unknown in algebra etc), after I + DENT + IT
26	ASBO - AS + BOy
29	IRON CURTAIN - I + RON + CURT + IN, around A
31	SUPERCHARGE - SUPER (short for superintendent) + CHARGE
33	ENDORSEMENT - END + OR (other ranks), + SENT around ME
36	SCREWDRIVER - cryptic indication, which I'm not convinced by - a screw is an unsound or broken-winded horse, not a dead one. A SCREWDRIVER is a type of cocktail
38	DIES - double definition (DIES is Latin for day)
39	STREAKED - RE in STAKED
41	SYLLABLED - ALLY'S (reversed) + BLED
44	PLEA BARGAIN - (a pal barge in)*
45	SPEEDWAY - Spooner's version would be "weeds pay"
48	EVAPORATE - EVA + P + ORATE
49	NERO - an "&lit" clue (i.e. one where the whole clue is both the cryptic indicator and the definition), with the the name hidden in fiNE ROman
50	KEROSENE - (sore knee)*
52	CLIQUE - CLUE around I Q
53	OLD-AGE PENSIONERS - (A person's gone idle)*. "Idle" doesn't describe most of the pensioners I know!
54	SINNER - SERmon around INN
55	TRADES ON - (so ardent)*
56	DASTARD - (drat + sad), reversed

Down
1	CORONA - double definition
2	UPTOWN - U + PT + (now)*
3	FIRST MATE - FIR + STATE around M
4	DRILLMASTER - (treadmills r)*
5	FOGY - FOGgY
6	INFORMATION - IN FORMATION (reference to formation dancing)
7	SMITHEREENS - SMITH, + SNEEREd reversed
8	FREE AGENT - double definition
10	INCHOATE - IN + CH + OrATE. INCHOATE means not yet formed or fully developed
11	GULLIVER'S TRAVELS - (vulgar verse still)*
12	SARGENT - Sky + ARGENT
15	COFACTOR - CO-ACTOR around F. A COFACTOR is a chemical that is needed for a protein - usually an enzyme - to function
19	DECREASE - DECREE around AS
22	SPLIT END - END appears, "split", in "Women definitely"
23	SECOND-GENERATION - "sage" could be defined by SECOND GENERATION, indicating S + AGE
27	OVERRIDE - ODE around V + ERR + Is, I think. I'm assuming that I is an alternative form of "Is", meaning island
28	THOR - THORn
30	CARP - CAR + Parking
32	PERISHER - double definition
34	EXTERNAL - ETERNAL around X
35	TAKEN IN HAND - TAKEN IN + HAND
36	SIDE STREETS - sounds like "side's treats"
37	WELL-DRESSED - double definition (refers to the well-dressing tradition in some Derbyshire villages)
40	ENAMELLER - hELLER around NAME
42	ANALOGOUS - A LOGO in AN US
43	ABSOLUTE - double definition; refers to Sir Anthony Absolute in the play "The Rivals" by Sheridan
44	PIERCES - PIECES around Road
46	GENEVA - (a + Ven + e.g.), reversed
47	LEASED - pLEASED
51	BEAN - BEANo - beano is an abbreviation for a "bean-feast"