Clue: Take unfair advantage of a private draw organised by Kelvin? (4,4)
Answer: PULL RANK
Explanation: Definition: Take unfair advantage of a private
 PULL(to draw/to exert a force that causes movement) + RAN(organised/managed by) K(symbol for the kelvin, the unit of temperature in the Kelvin temperature scale).
Defn: To take advantage of one's superior position/rank over another, possibly a lowly private in the military.