In US, smart retreat by black political leader (4,5)
I believe the answer is:
Here is my best explanation:
'political leader' is the definition.
'in us smart retreat by black' is the subsidiary indication.
'in us smart' becomes 'tony' (US term meaning fashionable).
'retreat' becomes 'lair'.
'by' is a charade indicator (letters next to each other).
'black' becomes 'b' (as in pencil classifications).
'lair' put after 'b' is 'blair'.
(Other definitions for tony blair that I've seen before include "Middle East envoy", "Politician - Tory in Lab (anag)" and "Prime Minister of the UK".)