Sat Times 25,574

[anikomo]

Cannot work out right hand corner and would appreciate help.
24a. Cathedral backing on to Roman square- fit for the best colleges,(3,6) I have I?? ?E???E
26a. Girl shortly appearing with order to wrap up one's cold snacks.(5) I have S???I
15d. Fateful day to hold swimming gala that's no real atmosphere.(5,3) I have ?D?A? ???
22d. Peloton member's extracted short clip for bag with fluid.(4) I have ???T

[boxtops]

26 Su-SH-I

[bibblebub]

ivy league
sushi
ideal gas
cyst

[vetuste_ennemi]

IV + y lE[rev] + ague
Ide(al ga[anag])s
cy[cli]st

[Lie-in King]

24a Ivy League - 'IV' (4, Roman; square [of 2]) + 'Ely' (cathedral, back) + 'ague' (fit)
26a Sushi (cold snacks) - 'Su(e)' (girl, shortly) + 'sh' (order to wrap up; be quiet) + 'i' (one)
15d Ideal gas - anag 'gala' (in) 'ides' (fateful day; "Ides of March", eg)
22d Cyst (bag with fluid) - remove 'cli(p)' (short, from) 'cyclist' (member of peloton)

[anikomo]

Very many thanks to you all---am really grateful for your help.