Solving time: 24:33 - with one mistake.

Quite a gentle Sunday solve this week, after last week's time-consuming Jumbo. I made one clumsy mistake at 2d due to not spending enough time parsing the wordplay. I though I might be on for a much quicker time, but I slowed down a lot in the SE corner, particularly on the 19a/13d combination which were my LOIs.

cd = cryptic def., dd = double def., rev = reversal, homophones are written in quotes, anagrams as (--)*, and removals like this

Across
1	I(R)AN
3	STIR-FRYING = (TRY RINGS IF)*
10	GEN + RE
11	ULAN BATOR = (N + LABOUR + AcT)* - The capital of Mongolia
12	OUT OF THE WINDOW - dd
14	TARQUIN = RAT (traitor) rev + QUIN (one of five) - Tarquin the Elder and Tarquin the Proud were two of the seven legendary Kings of Rome.
15	YIELDED - dd
17	MELODIC = MEL C about (I + DO) rev - Melanie Chisholm, aka Mel C or Sporty Spice, was one of the Spice Girls
19	LIB + R(I)UM
20	SQUADRON LEADER = (DAD QUARRELS + ONE)*
23	OVER + DRIVE
24	SKI(R)T
25	NANDROLONE = (NEAR LONDON)*
26	sAGES - or possibly mAGES, although that would more usually be MAGI
Down
1	IN GOOD TIME - dd - although generally, the phrase IN GOOD TIME means 'at the appropriate time' which on the whole is not quickly. However, when used in the sense of 'he made the journey in good time' then quickly is what's implied.
2	AU NATUREL = AUN(A)T + URE + L - I clumsily put AU NATURAL, thinking that Ural might be both a river and a lake, but it's just a river. It was only after submission when I discovered that I had one wrong that I realised my mistake.
4	TOUGHEN = (NOT HUGE)*
5	bROADWAY
6	ROBIN REDBREAST = (BARRISTER BONED)*
7	INT(R)O
8	GA(R)Y
9	NEWFOUNDLANDER = NEW (green) + LAND (light) in FOUNDER (sink)
13	ADUMBRATES = (DUMB + RATE) all in AS (while)
16	untangleD + WIND + LING
18	CORDIAL - dd
19	LANTERN - cd - a portable light
21	QUEEN - &lit - although it took me a while post-solve to see the wordplay. It's (QUEEN + TAILS) = (SEQUENTIAL)*, 'run' is being used as an anagrind.
22	DOWN - dd