Finally buy beer in university (4)
I believe the answer is:
yale
'university' is the definition.
(Yale university is an example)
'finally buy beer' is the wordplay.
'finally' suggests the final letters.
'beer' becomes 'ale' (I've seen this before).
The final letter of 'buy' is 'y'.
'y'+'ale'='YALE'
'in' acts as a link.
(Other definitions for yale that I've seen before include "security device" , "University man" , "US university; lock" , "US Ivy League college" , "Thief might gain entrance after picking this" .)