Crossword Genius

American politician's one foul trick (6)

Ross

I believe the answer is:

neocon

'american politician's' is the definition.
(US term for a neoconservative)

'one foul trick' is the wordplay.
'foul' indicates an anagram.
'trick' becomes 'con' (a con is a fraud or trick).
'one' is an anagram of 'neo'.
'neo'+'con'='NEOCON'

(Other definitions for neocon that I've seen before include "Someone advocating a new form of democratic capitalism" , "Traditionalist" , "politician on the right" , "Right-winger" , "A supporter of the policies of President George Bush? (abbr)" .)

I've seen this clue in The Guardian.
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