Artist Lichtenstein (3)
I believe the answer is:
roy
'artist lichtenstein' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for roy that I've seen before include "Rob . . . was a notorious Scottish outlaw" , "'Rob ..., ... Rogers (3)'" , "Man" , "'... Rogers, old film star cowboy (3)'" , "- Orbison, US singer" .)