Play higher card in game held by public representative (9)
I believe the answer is:
overtrump
'play higher card' is the definition.
'game held by public representative' is the wordplay.
'game' becomes 'ru' (rugby union).
'held by' is an insertion indicator.
'public' becomes 'overt' ('overt' is associated in meaning with 'public').
'representative' becomes 'mp'.
'overt'+'mp'='overtmp'
'ru' placed within 'overtmp' is 'OVERTRUMP'.
'in' acts as a link.
(Other definitions for overtrump that I've seen before include "play ace?" , "Win trick by playing higher card" , "use a superior club?" , "Way to take trick" , "Excel at trick" .)