Nudge given to one girl being extravagant (8)
I believe the answer is:
prodigal
'extravagant' is the definition.
('prodigal' can be similar in meaning to 'extravagant')
'nudge given to one girl' is the wordplay.
'nudge' becomes 'prod' ('prod' can be a synonym of 'nudge').
'given to' is a charade indicator (letters next to each other).
'one' becomes 'i' (Roman numeral).
'girl' becomes 'gal' ('gal' can be a synonym of 'girl'**).
'prod'+'i'+'gal'='PRODIGAL'
'being' is the link.
(Other definitions for prodigal that I've seen before include "Wasteful - gold pair (anag)" , "This son got the fatted calf" , "Grip load (anag.)" , "Spendthrift" , "Extravagant - lavish" .)