Forward, possibly not booked (10)

I believe the answer is:

unreserved

'forward' is the definition.

'not booked' is the wordplay.
'not' becomes 'un' (prefix meaning 'not').
'booked' becomes 'reserved' (similar in meaning).
'un'+'reserved'='UNRESERVED'

'possibly' acts as a link.

I've seen this clue in The Telegraph.

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