Cat runs after its prey (6)
I believe the answer is:
mouser
'cat' is the definition.
(mouser is a kind of cat)
'runs after its prey' is the wordplay.
I cannot really understand how this works, but
'runs' could be 'r' (cricket abbreviation) and 'r' is found within the answer.
The remaining letters 'mouse' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for mouser that I've seen before include "Cat proficient at catching small rodents" , "Rodent catcher" , "moggy" , "Cat that's good at catching small rodents" , "Cat with certain skills" .)