Stranger loitering around team, standing at the front gates (5)
I believe the answer is:
exits
'gates' is the definition.
(gate is a type of exit)
'stranger loitering around team standing at the front' is the wordplay.
'stranger' becomes 'ET' (short for extraterrestrial, an alien).
'loitering around' indicates putting letters inside.
'team' becomes 'xi' (eleven, a football team).
'at the front' says to take the initial letters.
The initial letter of 'standing' is 's'.
'et' placed around 'xi' is 'exit'.
'exit'+'s'='EXITS'
(Other definitions for exits that I've seen before include "Withdraws" , "Egresses" , "Ways out" , "Departs" , "Goes out, leaves" .)