Took action that fitted the bill without it (4)
I believe the answer is:
sued
'took action that' is the definition.
'sued' can be an answer for 'took action'. I'm unsure of the remainder of the definition.
'fitted the bill without it' is the wordplay.
'fitted the bill' becomes 'suited'.
'without' suggests deleting specific letters.
'suited' with 'it' taken away is 'SUED'.
(Other definitions for sued that I've seen before include "taken to court" , "Took legal action against" , "Brought an action against" , "Prosecuted" , "Started legal proceedings against (someone)" .)