Is it possible that adolescent is a mess? (7)
I believe the answer is:
canteen
'mess?' is the definition.
(both can mean a room for eating)
'is it possible that adolescent is a' is the wordplay.
I cannot really see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
'a' could be 'an' and 'an' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for canteen that I've seen before include "Pub in Jo'burg" , "Soldier's water-flask" , "Water container and works restaurant" , "Staff eating area" , "Workers' restaurant" .)