Fish in vehicle by edge of pool (4)
I believe the answer is:
carp
'fish' is the definition.
(I know that carp is a type of fish)
'vehicle by edge of pool' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle).
'by edge of pool' becomes 'p' (I can't explain this - if you can you should give a lot more credence to this answer).
'car'+'p'='CARP'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for carp that I've seen before include "Criticise - fish" , "Go on at" , "Nagging fish?" , "Continuously find fault" , "Continually nag; fish" .)