Plain land for Conservative statesman (7)
I believe the answer is:
baldwin
'conservative statesman' is the definition.
(20th-century prime minister Stanley Baldwin)
'plain land' is the wordplay.
'plain' becomes 'bald' (I've seen this before).
'land' becomes 'win'.
'bald'+'win'='BALDWIN'
'for' is the link.
(Other definitions for baldwin that I've seen before include "British statesman" , "Former PM" , "Medieval monarch - black American writer - British premier" , "Prime minister" , "British PM three times between WWI and WWII" .)