Brown coats unusual for top Democrat (6)
I believe the answer is:
'top democrat' is the definition.
(former US president Harry Truman)
'brown coats unusual' is the wordplay.
'brown' becomes 'tan' (tan is a kind of brown).
'coats' means one lot of letters goes inside another.
'unusual' becomes 'rum' (I've seen this before).
'tan' placed around 'rum' is 'TRUMAN'.
'for' is the link.
(Other definitions for truman that I've seen before include "- - Capote (lit.)" , "Harry S ..., former president of USA" , "American president who ordered use of atomic bomb" , "Harry S ... former US president" , "Harry S ...... was USA president 1945-53" .)