Some motorcyclists are leaving to frighten walkers (10)

I believe the answer is:

scramblers

'some motorcyclists' is the definition.

'are leaving to frighten walkers' is the wordplay.
'leaving' suggests deleting specific letters.
'to frighten' becomes 'scare' ('scare' can be a synonym of 'frighten').
'walkers' becomes 'ramblers' (rambler is a kind of walker**).
'scare' with 'are' taken away is 'sc'.
'sc'+'ramblers'='SCRAMBLERS'

I've seen this clue in The Independent.

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