Beer taken on, on one's own (5)
I believe the answer is:
alone
'on one's own' is the definition.
(I've seen this before)
'beer taken on' is the wordplay.
'beer' becomes 'ale' (I've seen this before).
'taken' is an insertion indicator.
'ale' placed around 'on' is 'ALONE'.
(Other definitions for alone that I've seen before include "without another" , "Without others being involved" , "Singly" , "On one's own" , "Note of charges" .)