Disastrously dropped litre drinks in school (9)
I believe the answer is:
collapsed
'disastrously dropped' is the definition.
'litre drinks in school' is the wordplay.
'litre' becomes 'l' ('l' can be a synonym of 'litre').
'drinks' becomes 'laps' (lapping is a kind of drinking**).
'in' indicates putting letters inside.
'school' becomes 'coed' (I've seen this before).
'l'+'laps'='llaps'
'llaps' inserted inside 'coed' is 'COLLAPSED'.
(Other definitions for collapsed that I've seen before include "Fell apart" , "laid low" , "Gave way, caved in" , "Cracked up - gave way" .)