Who works on toes held by footballer in agony (9)
I believe the answer is:
ballerina
'who works on toes' is the definition.
'held by footballer in agony' is the wordplay.
'held by' says the answer is hidden in the clue.
'BALLERINA' can be found hidden inside 'footballer in agony'.
(Other definitions for ballerina that I've seen before include "Female classical dancer" , "agile performer" , "lass good at splits?" , "Danseuse" , "girl from the Kirov?" .)