Fourth-down specialist (6)
I believe the answer is:
punter
'fourth-down specialist' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for punter that I've seen before include "boater" , "Better - rugby player - river boatman" , "Gambler; customer" , "Person who bets" , "Professional gambler; client (inf.)" .)