Wasted young lady to hedge bet finally (8)
I believe the answer is:
misspent
'wasted' is the definition.
(I've seen this before)
'young lady to hedge bet finally' is the wordplay.
'young lady' becomes 'miss' (synonyms).
'to hedge' becomes 'pen' (both can mean to surround or enclose).
'finally' indicates one should take the final letters.
The final letter of 'bet' is 't'.
'miss'+'pen'+'t'='MISSPENT'
(Other definitions for misspent that I've seen before include "troublesome youth?" , "Wasted (as youth)" , "Squandered" , "wasted away?" , "having used money unwisely" .)