Map-makers engaging chaps producing signs (5)
I believe the answer is:
omens
'signs' is the definition.
(omen is a kind of sign)
'map-makers engaging chaps' is the wordplay.
'map-makers' becomes 'os' (Ordnance Survey).
'engaging' is an insertion indicator.
'chaps' becomes 'men' (I've seen this before).
'os' placed around 'men' is 'OMENS'.
'producing' acts as a link.
(Other definitions for omens that I've seen before include "Prognostications" , "Augurs" , "Signs of things to come" , "Harbingers, portents" , "Auguries" .)