Fellow left with total for bet (7)
I believe the answer is:
flutter
'for bet' is the definition.
(to have a flutter is to put a bet on)
'fellow left with total' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'left' becomes 'l' (common abbreviation).
'with' says to put letters next to each other.
'total' becomes 'utter' (I've seen this in another clue).
'f'+'l'+'utter'='FLUTTER'
(Other definitions for flutter that I've seen before include "Informally a slight gamble as on a horse" , "Bat" , "Small bet; beat feebly" , "Move one's eyelashes - move like a butterfly - bet" , "Fly unsteadily; small bet" .)