Britain enters whopper motor event quite freely (9)

I believe the answer is:

liberally

'quite freely' is the definition.
(in a free or liberal way)

'britain enters whopper motor event' is the wordplay.
'britain' becomes 'B' (common abbreviation as in GB).
'enters' means one lot of letters goes inside another.
'whopper' becomes 'lie' (whopper can mean an outrageous lie).
'motor event' becomes 'rally' (I've seen this before).
'b' inserted inside 'lie' is 'libe'.
'libe'+'rally'='LIBERALLY'

I've seen this clue in The Guardian.

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