Fox should cover conflict once in progress (6)

I believe the answer is:

toward

'once in progress' is the definition.
('toward' could once mean 'in progress')

'fox should cover conflict' is the wordplay.
'fox' becomes 'tod' (historic term).
'should cover' is an insertion indicator.
'conflict' becomes 'war' (war is a kind of conflict).
'tod' going around 'war' is 'TOWARD'.

(Another definition for toward that I've seen is " In the direction of".)

I've seen this clue in The Times.

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