Rugby union team (7)
I believe the answer is:
fifteen
'rugby union team' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for fifteen that I've seen before include "No. of men on dead man's chest (Stevenson)" , "Longish odds - 7" , "XV" , "Square root of two hundred and twenty-five" , "Film type" .)