Moon-landing program (6)
I believe the answer is:
apollo
'moon-landing program' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for apollo that I've seen before include "US moon landing programme" , "Handsome Greek god" , "handsome youth" , "Greek sun god and leader of the Muses" , "handsome chap" .)