### Clue: Figure on board supporting Labour politician, sham opponent (5,3)
### Answer: STRAW MAN 
 ### Explanation: Definition: sham opponent
 MAN(a piece on a chess board) **placed below**(supporting) STRAW(Jack, British Labour politician).
Defn: A made-up, conveniently weak version of one's argument or position presented by one's opponent, so that the latter can easily tear it down.