Short trough that may irritate dog (5)
I believe the answer is:
mange
'short trough that may irritate dog' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'short trough' is the wordplay.
'short' means to remove the last letter.
'trough' becomes 'manger' (synonyms).
'manger' with its last letter taken off is 'MANGE'.
Can you help me to learn more?
(Other definitions for mange that I've seen before include "Skin disease of cats and dogs" , "Domestic animals may find it very irritating" , "Itchy disease in dogs, etc" , "disease results" , "may have to deal with this" .)