I leave Elsie instead (4)
I believe the answer is:
else
'instead' is the definition.
(I've seen this in another clue)
'i leave elsie' is the wordplay.
'leave' suggests deleting specific letters.
'elsie' with 'i' taken away is 'ELSE'.
(Other definitions for else that I've seen before include "Otherwise; different from" , "Besides; instead" , "Adverb meaning if not, otherwise" , "Eels (anag)" , "As an alternative" .)