Bounder caught a duchess (3)
I believe the answer is:
cad
'bounder' is the definition.
(synonyms)
'caught a duchess' is the wordplay.
'caught' becomes 'ca' (I've seen this in other clues).
'a duchess' becomes 'd' (this could be a standard abbreviation which I don't know about).
'ca'+'d'='CAD'
Can you help me to learn more?
(Other definitions for cad that I've seen before include "Dishonourable man of decadent sort" , "Heel" , "Stinker" , "A knave, real rotter" , "A rotten chap, no integrity" .)