Settler Mark is taking time (8)
I believe the answer is:
colonist
'settler' is the definition.
('colonist' can be a synonym of 'settler')
'mark is taking time' is the wordplay.
'mark' becomes 'colon' (colon is a kind of mark**).
'taking' means one lot of letters go next to another.
'time' becomes 't'.
'colon'+'is'+'t'='COLONIST'
(Other definitions for colonist that I've seen before include "Settler" , "Immigrant" , "I'll settle" , "Coin slot (anag.)" .)