Bill upset club (3)
I believe the answer is:
tab
'bill' is the definition.
(tab is a kind of bill)
'upset club' is the wordplay.
'upset' says the letters should be written in reverse.
'club' becomes 'bat' (bat is a kind of club).
'bat' reversed gives 'TAB'.
(Other definitions for tab that I've seen before include "Tag" , "Small flap - bill" , "Tally of orders in bar" , "Running bar bill" , "Check" .)