Really popular result (2,6)
I believe the answer is:
in effect
'really' is the definition.
(thesaurus)
'popular result' is the wordplay.
'popular' becomes 'in'.
'result' becomes 'effect' ('effect' can be a synonym of 'result').
'in'+'effect'='IN EFFECT'
(Other definitions for in effect that I've seen before include "Really; operating" , "to all intents and purposes" , "Really, as a matter of fact" , "Operating; to all intents" , "Really, or in essence" .)