Solution to 18A has been deliberately left unsolved and is to be answered only by a non-regular / novice commenter, with proper annotation. Those who have answered earlier in the week, please give others a chance.
Open for anyone to answer, if not solved by 1 PM.
ACROSS
5 Yankee tie, crest and official garments (5-3) STAND-OFF [T]
9 Dope is worthless - contains adulterated musk (8) NUMSKULL {N{MUSK*}ULL}
10 Double-woven blouse, extremely lacy, worn by women (3-3) TWO-PLY TOP}{LacY} over {W}
11 Bubbly unopened alcohol is toted after the start in sign of childhood camaraderie (3,6,3) OLD SCHOOL TIE {aLCOHOL+IS+tOTED}*
13 Ducks in a row? (4) PAIR [CD]
14 12 eggs found in nobleman's jacket - issue being reviewed (8) NOONTIME {00} in {No...aN}{EMIT<=}
17 Vocal and essentially cynical freak subject to emotional fits (8) VOLCANIC {VOCAL+cyNICal}*
18 75% of 14 is 5 less? (4) N?N?
20 Reserve hospital taken over by sick senior civil servant? (6-6) OFFICE-HOLDER {ICE}{H} in {OFF}{OLDER}
25 Bust without head, feels very hard (8) SEVERELY {fEELS+VERY}*
26 Time for cold drink and sweet (6) TOFFEE (+t-c)TOFFEE
DOWN
2 Hammer ball into channel (4) ROUT {R{O}UT}
4 Obstinate Republican boards train (6) STURDY {STU{R}DY}
5 Silly Conservative focuses on reforms with intense third party scrutiny (4-11) SELF-CONSCIOUSLY {SILLY+C+FOCUSES+ON}*
8 British daily featuring extremely unusual, shortened clip on soldiers' execution (10) FULFILMENT {FT} over {Un...aL}{FILm}{MEN}
12 Reached outside old University with standard mask (10) CAMOUFLAGE {CAM{O}{U}{FLAG}E}
19 Aimless commercial break (6) ADRIFT {AD}{RIFT}
21 1-0; United (2,3) IN ONE {1}{NONE}
22 Regularly connected in the past (4) ONCE {cOnNeCtEd}
Reference List
Husband = H, Women = W, Reserve = ICE, Hospital = H, Time = T, Cold = C, Black = B, Rat = SHOP, Second = S, Republican = R, Conservative = C, Soldiers = MEN, Old = O, University = U, Commercial = AD