Utterly determined, this man will gamble around noon (4-4)
I believe the answer is:
hell-bent
'utterly determined' is the definition.
(I know this)
'man will gamble around noon' is the wordplay.
'man will' becomes 'hell' ('he'll', contraction of 'he will').
'gamble' becomes 'bet' (bet is a kind of gamble).
'around' is an insertion indicator.
'noon' becomes 'n' (abbreviation for noon).
'bet' going around 'n' is 'bent'.
'hell'+'bent'='HELL-BENT'
'this' acts as a link.
(Other definitions for hell-bent that I've seen before include "Recklessly determined" , "Determined at all costs" , "on path with good intentions" , "Absolutely determined" , "Dogged - persistent" .)