Animal catcher spies boss by a river mouth (9)
I believe the answer is:
mousetrap
'spies boss by a river mouth' is the definition.
I can't tell whether this definition defines the answer.
'animal catcher' is the wordplay.
'animal' becomes 'mouse' (mouse is a kind of animal).
'catcher' becomes 'trap' (I've seen this in another clue).
'mouse'+'trap'='MOUSETRAP'
Can you help me to learn more?
(Other definitions for mousetrap that I've seen before include "Poor cheese (colloq.)" , "Cheese-baited snare" , "This may take the Mickey" , "Boring hard cheese (informal)" , "For instance, old Cheshire" .)