Stable men are upset by less rot (7)
I believe the answer is:
ostlers
'stable men' is the definition.
The definition and answer can be both people as well as being plural nouns.
Maybe there's an association between them I don't understand?
'upset by less rot' is the wordplay.
'upset by' indicates an anagram.
'less'+'rot'='lessrot'
'lessrot' anagrammed gives 'OSTLERS'.
'are' acts as a link.
Can you help me to learn more?
(Other definitions for ostlers that I've seen before include "Historically they looked after the horses at an inn" , "Let Ross join in group of old stable managers" , "Stablemen at inns of old" , "They used to stable horses at inns" , "They looked after the horses at the inns of old" .)