Male animals catching fox's nits (8)

I believe the answer is:

tomfools

I'm a little stuck... Click here to teach me more about this clue!

'fox's nits' is the definition.
Although both the answer and definition are plural nouns, I don't see how they can define each other.

'male animals' is the wordplay.
'male' becomes 'tom' (tom can mean a male cat).
'animals' becomes 'fools' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'tom'+'fools'='TOMFOOLS'

'catching' is the link.

Can you help me to learn more?

I've seen this clue in The Independent.

Want a hint initially instead of a full solution? Install my app