Fitness of cheeky drinking toast? (4,6)

I believe the answer is:

rude health

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

'fitness' is the definition.
I don't know anything about this answer so I cannot judge whether this works.

'cheeky drinking toast?' is the wordplay.
'cheeky drinking' becomes 'rude' (I can't justify this - if you can you should give a lot more credence to this answer).
'toast?' becomes 'health' (I've seen this before).
'rude'+'health'='RUDE HEALTH'

'of' acts as a link.

Can you help me to learn more?

I've seen this clue in The Guardian.

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