Promote development of New Forest (6)
I believe the answer is:
foster
'promote development' is the definition.
(I've seen this before)
'new forest' is the wordplay.
'new' is an anagram indicator.
'forest' with letters rearranged gives 'FOSTER'.
'of' acts as a link.
(Other definitions for foster that I've seen before include "Nurse -- nursery rhyme doctor" , "Nurture, bring up" , "Nurture and rear" , "advance" , "Old woodman" .)