Wound grand tree (4)
I believe the answer is:
gash
'wound' is the definition.
(gash is a kind of wound)
'grand tree' is the wordplay.
'grand' becomes 'g' ('G' can be a synonym of 'grand'**).
'tree' becomes 'ash' (ash is a kind of tree).
'g'+'ash'='GASH'
(Other definitions for gash that I've seen before include "Jagged cut" , "Spare - rubbish" , "Laceration" , "Open wound" , "Wound made by cutting" .)