Experience support with stadium (10)
I believe the answer is:
background
'experience' is the definition.
(eg someone's professional background)
'support with stadium' is the wordplay.
'support' becomes 'back' (to back is to support or endorse).
'with' is a charade indicator (letters next to each other).
'stadium' becomes 'ground' (eg a football ground).
'back'+'ground'='BACKGROUND'
(Other definitions for background that I've seen before include "history" , "player's obscure position" , "inconspicuous position" , "Reason behind" , "Environment" .)