Pop artist Lichtenstein (3)
I believe the answer is:
roy
'pop artist lichtenstein' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for roy that I've seen before include "-- Lichtenstein, US artist" , "- Orbison, US singer" , "Rob --, Scots outlaw" , "Rob . . . was a notorious Scottish outlaw" , "Rob .... was a famous Scottish bandit" .)