Disheartened Ezekiel quits team (6)
I believe the answer is:
'team' is the definition.
(eleven is a kind of team)
'disheartened ezekiel quits' is the wordplay.
'disheartened' suggests removing the centre.
'quits' becomes 'even' (as in 'call it quits').
'ezekiel' with its centre taken out is 'el'.
(Other definitions for eleven that I've seen before include "Players", "Cardinal", "Not first team (6,6) - See 24", "Number of pipers piping", "Late".)