Youth party steeped in beer smell (10)
I believe the answer is:
adolescent
'youth' is the definition.
(I've seen this before)
'party steeped in beer smell' is the wordplay.
'party' becomes 'do' (do is a kind of party).
'steeped in' indicates putting letters inside (I've seen this in other clues).
'beer' becomes 'ale' (type of beer).
'smell' becomes 'scent' (synonyms).
'do' going within 'ale' is 'adole'.
'adole'+'scent'='ADOLESCENT'
(Other definitions for adolescent that I've seen before include "juvenile" , "At the stage between childhood and maturity" , "sixth-former, say" , "Teenage" , "One growing" .)