Engaged in forensics (6)
I believe the answer is:
argued
'engaged in forensics' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for argued that I've seen before include "Contended or debated" , "Disputed, opposed verbally" , "Rag due (anag.)" , "Quarrelled or debated" , "Sought to show by reasoning" .)