Singer Acuff (3)
I believe the answer is:
roy
'singer acuff' 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 "- Orbison, US singer" , "Rob . . . was a famous Scottish outlaw" , "Rob . . . was a notorious Scottish outlaw" , "'... Rogers, old film star cowboy (3)'" , "Man" .)