Excited gambler may have this (8)
I believe the answer is:
aflutter
This clue is a double definition.
'excited' is the first definition.
(similar in meaning)
'gambler may have this' is the second definition.
(to have a flutter is to put a bet on)
(Other definitions for aflutter that I've seen before include "in excited state" , "is rather nervous" , "Nervous, twitchy" , "Agitated - excited (eg in anticipation)" , "trembling" .)