A team's pivot (4)
I believe the answer is:
axis
'pivot' is the definition.
(I've seen this in another clue)
'a team's' is the wordplay.
'team's' becomes 'XI's' (a football team, from Roman numerals for 11).
'a'+'xis'='AXIS'
(Other definitions for axis that I've seen before include "Line through the middle" , "Fixed line in revolution" , "all revolves around this" , "Line of symmetry" , "Body's line of rotation" .)