Bigger when right into beer (6)
I believe the answer is:
larger
'bigger' is the definition.
('large' can be a synonym of 'big')
'right into beer' is the wordplay.
'right' becomes 'r' (common abbreviation).
'into' is an insertion indicator.
'beer' becomes 'lager' (type of beer).
'r' put within 'lager' is 'LARGER'.
'when' acts as a link.
(Other definitions for larger that I've seen before include "More comprehensive" , "Greater in size" , "Comparatively big" , "Ebullient person may be describes as ?? than life" , "Comparatively bigger" .)