Indigenous trees primarily planted in green (6)
I believe the answer is:
native
'indigenous' is the definition.
(similar in meaning)
'trees primarily planted in green' is the wordplay.
'primarily' says to take the initial letters.
'planted in' is an insertion indicator.
'green' becomes 'naive' (similar in meaning).
The first letter of 'trees' is 't'.
't' inserted inside 'naive' is 'NATIVE'.
(Other definitions for native that I've seen before include "Son" , "One born in a certain place" , "Indigenous person" , "One who belongs to place by birth" , "Resident" .)