Approve a party exercise (5)
I believe the answer is:
adopt
'approve' is the definition.
(thesaurus)
'a party exercise' is the wordplay.
'party' becomes 'do' (do is a kind of party).
'exercise' becomes 'pt'.
'a'+'do'+'pt'='ADOPT'
(Other definitions for adopt that I've seen before include "Accept as one's own" , "Take into one's family" , "Formally approve" , "Take responsibility for" , "choose as candidate" .)