The guys are on the hilltop with a guide (6)
I believe the answer is:
mentor
'a guide' is the definition.
(I've seen this in another clue)
'the guys are on the hilltop' is the wordplay.
'the guys' becomes 'men' (guy can mean a man).
'are on' is a charade indicator (letters next to each other).
'the hilltop' becomes 'tor' (I've seen this in another clue).
'men'+'tor'='MENTOR'
'with' acts as a link.
(Other definitions for mentor that I've seen before include "A trusted teacher or counsellor" , ""Guide, philosopher, and friend"" , "One guiding" , "A wise and experienced teacher" , "Merton (anag.)" .)