Drop first-class group game (7)
I believe the answer is:
abandon
'drop' is the definition.
(thesaurus)
'first-class group game' is the wordplay.
'first-class' becomes 'A' (as in A-list, A-team etc).
'group' becomes 'band' (band can mean a group of people).
'game' becomes 'on' (both can mean willing).
'a'+'band'+'on'='ABANDON'
(Other definitions for abandon that I've seen before include "Cast aside" , "Desert, strand" , "Completely give up; desert" , "Leave behind - licentiousness" , "Desert; intemperance" .)