Revolver found by soldiers climbing rocky peak (5)
I believe the answer is:
'revolver' is the definition.
(something which revolves)
'by soldiers climbing rocky peak' is the wordplay.
'by' says to put letters next to each other.
'soldiers' becomes 'OR' (Other Ranks).
'climbing' says the letters should be written in reverse (in a down clue, letters climb up).
'rocky peak' becomes 'tor' (a tor is a rocky hill).
'or' written backwards gives 'ro'.
'ro'+'tor' is 'ROTOR'.
'found' is the link.
(Other definitions for rotor that I've seen before include "Helicopter propeller" , "The machine part moves in a circle" , "... and another" , "Revolving part of a motor" , "Turner" .)