Bob Mortimer's one to catch zero carp (4)
I believe the answer is:
moan
'carp' is the definition.
The definition and answer can be both to do with communicating as well as being verbs in their base form.
Maybe there's an association between them I don't understand?
'bob mortimer's one to catch zero' is the wordplay.
'bob mortimer' becomes 'm' (I can't explain this - if you can you should give a lot more credence to this answer).
'one' becomes 'an' (an apple is one apple).
'to catch' is an insertion indicator.
'zero' becomes 'O' (O resembles 0).
'm'+'an'='man'
'man' placed around 'o' is 'MOAN'.
Can you help me to learn more?
(Other definitions for moan that I've seen before include "Express pain" , "Keen" , "Whinge" , "Murmur of pain; grumble" , "Bewail" .)