Make fun of staff breaking into earnings (6)
I believe the answer is:
parody
'make fun of' is the definition.
(thesaurus)
'staff breaking into earnings' is the wordplay.
'staff' becomes 'rod' (I've seen this before).
'breaking into' is an insertion indicator.
'earnings' becomes 'pay' ('pay' can be a synonym of 'earnings').
'rod' going into 'pay' is 'PARODY'.
(Other definitions for parody that I've seen before include "Takeoff" , "Take off" , "a lampoon or comic imitation" , "Spoof, lampoon" , "Satire - burlesque" .)