It's come to be expected that Irish donkey will use these routes (8)

'it's come to be expected that irish donkey will use these routes' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.

'it's come to be expected that irish donkey will use these routes' is the wordplay.
I cannot quite see how this works, but
'routes' could be 'ways' (I've seen this in another clue) and 'ways' is found within the answer.
'it' could be 'sa' (old-fashioned abbreviation for sex appeal) and 'sa' is present in the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?