A businessman and his former wife having a drink (8)
I believe the answer is:
exporter
'a businessman and his' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'former wife having a drink' is the wordplay.
'former wife' becomes 'ex' (an ex-wife).
'having' is a charade indicator (letters next to each other).
'a drink' becomes 'porter' (porter is a kind of drink).
'ex'+'porter'='EXPORTER'
Can you help me to learn more?
(Other definitions for exporter that I've seen before include "Business that sells its goods abroad" , "one sells abroad" , "One selling abroad" , "Overseas trader" , "trading abroad" .)