City game to lift boycott (5)
I believe the answer is:
urban
'city' is the definition.
(thesaurus)
'game to lift boycott' is the wordplay.
'game' becomes 'ru' (rugby union).
'to lift' says the letters should be written backwards (in a down clue, letters lift up).
'boycott' becomes 'ban'.
'ru' reversed gives 'ur'.
'ur'+'ban'='URBAN'
(Other definitions for urban that I've seen before include "City - pope" , "Relating to a town or city" , "Had this description of town" , "One of eight popes" , "Non-rural" .)