7 down
Part
of
cog
starts
to
aggravate
cyclist’s
healthy
exercise
–
such
a
pain
(9)
Part of cog starts to aggravate cyclist’s healthy exercise – such a pain (9)
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hints
The definition is at the end of the clue.
How the clue works
Right, so such a pain at the end is your definition — that's what a TOOTHACHE is. For the wordplay, "Part of cog" gives you TOOTH, since a cog is made up of teeth, and then you take the starts to of "aggravate cyclist's healthy exercise" to spell out ACHE. Stick TOOTH and ACHE together and there's your toothache.