Grassy land in part needed for fold (5)
I believe the answer is:
pleat
'fold' is the definition.
(pleat is a kind of fold)
'grassy land in part' is the wordplay.
'grassy land' becomes 'lea' (I've seen this before).
'in' is an insertion indicator.
'part' becomes 'pt' (abbreviation).
'lea' placed inside 'pt' is 'PLEAT'.
'needed for' acts as a link.
(Other definitions for pleat that I've seen before include "Crease" , "Fold in a skirt" , "work on skirt?" , "Type of fold in fabric" , "Tuck" .)