Leading actor in Red Dwarf perhaps (4)
I believe the answer is:
star
This clue is a double definition.
'leading actor' is the first definition.
(eg the star of the show)
'red dwarf perhaps' is the second definition.
(red dwarf is a kind of star)
'in' acts as a link.
(Other definitions for star that I've seen before include "Big name" , "Principal actor in a film" , "Ball of fire" , "White blaze on a horse's forehead" , "Celestial body of hot gases" .)