Excel in public work (7)
I believe the answer is:
overtop
'excel' is the definition.
(thesaurus)
'public work' is the wordplay.
'public' becomes 'overt' ('overt' is associated in meaning with 'public').
'work' becomes 'op' (abbreviation for opus).
'overt'+'op'='OVERTOP'
'in' acts as a link.
(Other definitions for overtop that I've seen before include "Excel" , "Rise above" , "best" , "Exceed in height" , "Surpass (one may go " ____ the ___")" .)