Cycling competitor's additional clause? (5)

I believe the answer is:

rider

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'additional clause?' is the definition.
(additional clause on a contract or agreement)

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(Other definitions for rider that I've seen before include "Additional bit" , "Extra provision" , "Jockey" , "Equestrian addition by a jury" , "One on horse or bike" .)

I've seen this clue in The Sun.

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