Share beer and philosophy (9)
I believe the answer is:
rationale
'philosophy' is the definition.
(thesaurus)
'share beer' is the wordplay.
'share' becomes 'ration' (ration is a kind of share).
'beer' becomes 'ale' (I've seen this before).
'ration'+'ale'='RATIONALE'
'and' acts as a link.
(Other definitions for rationale that I've seen before include "Philosophy" , "Basis of logic" , "Logical reason for action" , "Underlying principle" , "Logic, reasoning" .)