Popular officer, by and large (2,7)
I believe the answer is:
in general
'by and large' is the definition.
(I've seen this before)
'popular officer' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'officer' becomes 'general' (general officer is a kind of officer).
'in'+'general'='IN GENERAL'
(Other definitions for in general that I've seen before include "Overall" , "Usually; mainly" , "by and large" , "Mostly" , "Where soldiers should have faith" .)