Unity of chaps evident in a salute (9)
I believe the answer is:
agreement
'unity' is the definition.
(thesaurus)
'chaps evident in a salute' is the wordplay.
'chaps' becomes 'men' (I've seen this before).
'evident in' indicates putting letters inside.
'salute' becomes 'greet' (I've seen this before).
'a'+'greet'='agreet'
'men' inserted into 'agreet' is 'AGREEMENT'.
'of' is the link.
(Other definitions for agreement that I've seen before include "Compact, accord" , "match" , "in sympathy" , "deal" , "Harmony or treaty" .)