Drunk intended to grab woman’s bottom: big deal? (4,7)

I believe the answer is:

high finance

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

'big deal?' is the definition.
I don't know anything about this answer so I can't judge whether this works.

'drunk intended to grab woman's bottom' is the wordplay.
'drunk' becomes 'high' (I've seen this before).
'intended' becomes 'fiance' (someone's 'intended' is who they are due to marry).
'to grab' is an insertion indicator.
'bottom' indicates one should take the final letters.
The final letter of 'woman' is 'n'.
'fiance' going around 'n' is 'finance'.
'high'+'finance'='HIGH FINANCE'

Can you help me to learn more?

(Other definitions for high finance that I've seen before include "Large, complex (and shady?) money transactions" , "management of large sums" .)

I've seen this clue in The Guardian.

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