Excited by a small bet (8)
I believe the answer is:
aflutter
'excited' is the definition.
(similar in meaning)
'by a small bet' is the wordplay.
'by' means one lot of letters go next to another.
'small bet' becomes 'flutter' (I've seen this before).
'a' put next to 'flutter' is 'AFLUTTER'.
(Other definitions for aflutter that I've seen before include "in excited state" , "trembling" , "is rather nervous" , "Nervous, twitchy" , "Agitated - excited (eg in anticipation)" .)