Colonize (6)
I believe the answer is:
settle
'colonize' is the definition.
(I know that colonize is a more specific form of settle)
This is the entire clue.
(Other definitions for settle that I've seen before include "perch" , "Reach an agreement or become calm" , "Become established or pay bill" , "somewhere in North Yorkshire" , "Come to rest -- North Yorkshire market town" .)