Small bet (7)
I believe the answer is:
flutter
'small bet' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for flutter that I've seen before include "Move one's eyelashes - move like a butterfly - bet" , "Bat" , "Fly unsteadily; small bet" , "Informally a slight gamble as on a horse" , "Small bet; beat feebly" .)