Expects, when on tries to find (5,3)

'expects' is the definition.
(looking for is a kind of expecting)

'on tries to find' is the wordplay.
I cannot really see how this works, but
'on' could be 'o' (I've seen this in other clues) and 'o' is found within the answer.
'to' could be 'for' and 'for' is found within the answer.
This may be the basis of clue (or it may be nonsense).

'when' is the link.

Can you help me to learn more?