Vision of some past foxtrot champion retaining beat (9)
I believe the answer is:
flashback
'vision of some past' is the definition.
(a flashback flashes back to the past)
'foxtrot champion retaining beat' is the wordplay.
'foxtrot' becomes 'f' (phonetic alphabet: alpha, bravo, charlie etc.).
'champion' becomes 'back' (I've seen this in other clues).
'retaining' means one lot of letters goes inside another (inserted letters are held or retained).
'beat' becomes 'lash' (lash can mean to beat as punishment).
'f'+'back'='fback'
'fback' going around 'lash' is 'FLASHBACK'.
(Other definitions for flashback that I've seen before include "Scene depicting previous events" , "(Transition to) earlier scene" , "Past scene inserted into a film's chronology" , "Past scene re-enacted" , "Disturbing sudden vivid memory of a past event" .)