He's not in an office but catching fish in the country (9)
I believe the answer is:
freelance
'he's not in an office but' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'fish in the country' is the wordplay.
'fish' becomes 'eel' (eel is a kind of fish).
'in the' indicates putting letters inside.
'country' becomes 'france' (France is an example).
'eel' put within 'france' is 'FREELANCE'.
'catching' is the link.
Can you help me to learn more?
(Other definitions for freelance that I've seen before include "Self-employed worker for hire" , "Not tied to employer" , "without regular work?" , "Self-employed person offering services where needed" , "Independent" .)