Youth after vessel, water bottle (7)
I believe the answer is:
canteen
'water bottle' is the definition.
'canteen' can be an answer for 'bottle' (canteen is a kind of bottle). I'm not certain of the 'water' bit.
'youth after vessel' is the wordplay.
'youth' becomes 'teen' (teenager).
'after' means one lot of letters go next to another.
'vessel' becomes 'can' (type of container).
'teen' after 'can' is 'CANTEEN'.
Can you help me to learn more?
(Other definitions for canteen that I've seen before include "Workplace restaurant" , "Pub in Jo'burg" , "Workplace eatery" , "Staff eating area" , "Works'' restaurant - cutlery" .)