Attack command (3)
I believe the answer is:
sic
'attack command' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sic that I've seen before include "Thus, sounds ill" , "Thus in Corsica" , "Word to call attention to a quoted mistake" , "Written exactly thus" , "'Thus, in printing (3)'" .)