Alternatively, stewed eels (4)
I believe the answer is:
else
'alternatively' is the definition.
(I've seen this before)
'stewed eels' is the wordplay.
'stewed' indicates an anagram.
'eels' is an anagram of 'ELSE'.
(Other definitions for else that I've seen before include "Besides; different" , "Adverb meaning if not, otherwise" , "Besides, otherwise" , "Alternatively" , "Besides; instead" .)