TV alien (3)
I believe the answer is:
alf
'tv alien' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for alf that I've seen before include "- Ramsey, England manager in nineteen sixty six" , "Mr Garnett" , "Great king briefly" , "-- Garnett, bigoted TV?character" , "Boy" .)