Get comfortable with republican colonist (7)
I believe the answer is:
settler
'colonist' is the definition.
(I know that colonist can be written as settler)
'get comfortable with republican' is the wordplay.
'get comfortable' becomes 'settle' (I've seen this before).
'with' means one lot of letters go next to another.
'republican' becomes 'R' (abbreviation in US politics).
'settle'+'r'='SETTLER'
(Other definitions for settler that I've seen before include "One colonising new area" , "Colonist, pioneer" , "Early mover into an area" , "Coloniser - arbitrator" , "new inhabitant" .)