Unselfish group member: "Pay me later for working'' (4,6)
I believe the answer is:
team player
'unselfish group member' is the definition.
'pay me later for working''' is the wordplay.
'pay me later' anagrams to 'TEAM PLAYER'.
But, I'm not clear how this is indicated.
(Other definitions for team player that I've seen before include "One who works well with others" , "One working well with colleagues" , "Cooperative type" , "not a man without side?" .)