Brown keeping Blair perhaps in post? (7)
I believe the answer is:
topmast
'post?' is the definition.
(I have seen 'high post' mean 'topmast' so perhaps 'post' could also mean 'topmast')
'brown keeping blair perhaps' is the wordplay.
'brown' becomes 'toast' (to brown something is to toast it).
'keeping' is an insertion indicator.
'blair perhaps' becomes 'pm' (abbreviation for prime minister - Tony Blair).
'toast' going around 'pm' is 'TOPMAST'.
'in' is the link.
(Other definitions for topmast that I've seen before include "Most apt (anag) - feature of a square-rigged ship" , "high post" , "post on board" , "Part of square-rigged ship" , "High part of sailing ship" .)