Feels elated inside, besides (4)
I believe the answer is:
else
'besides' is the definition.
(I've seen this in another clue)
'feels elated inside' is the wordplay.
'inside' says the answer is hidden in the clue.
'ELSE' is hidden in the letters of 'feels elated'.
(Other definitions for else that I've seen before include "In addition; different" , "Otherwise; different from" , "Besides, otherwise" , "Besides; different" , "Besides; instead" .)