Crude form of fishing (6)
I believe the answer is:
'crude' is the definition.
'form of fishing' is the wordplay.
I cannot quite see how this works, but
'of' could be 'o' and 'o' is present in the answer.
The remaining letters 'carse' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for coarse that I've seen before include "Rought or crude" , "Unpolished -- ribald" , "Vulgar; not fine" , "Rough in texture or crude in manner" , "Unrefined; rough" .)