Communist turning on soldier, one in procession (7)

I believe the answer is:

parader

'one in procession' is the definition.
(participant in a parade)

'communist turning on soldier' is the wordplay.
'communist' becomes 'red' (red can informally mean communist).
'turning' shows that the letters should be reversed in order.
'on' is a charade indicator (letters next to each other).
'soldier' becomes 'para' (short for paratrouper).
'red' in reverse letter order is 'der'.
'der' put after 'para' is 'PARADER'.

I've seen this clue in The Times.

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