Fellow leaving tree in swamp for wood (5)
I believe the answer is:
grove
'wood' is the definition.
(grove is a kind of wood)
'fellow leaving tree in swamp' is the wordplay.
'fellow' becomes 'man' (I've seen this before).
'leaving' is a deletion indicator.
'tree in swamp' becomes 'mangrove'.
'mangrove' with 'man' taken away is 'GROVE'.
'for' acts as a link.
(Other definitions for grove that I've seen before include "Dictionary-maker" , "Writer on music" , "Wood of small size" , "Small woodland" , "small plantation" .)