Well-worn stuff given to horse? (7)
I believe the answer is:
corncob
'well-worn stuff' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'to horse?' is the wordplay.
'to' becomes 'corn' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'horse?' becomes 'cob' (cob is a kind of horse).
'corn'+'cob'='CORNCOB'
'given' acts as a link.
Can you help me to learn more?
(Other definitions for corncob that I've seen before include "Head of maize" , "Hard section of a ear of maize" , "Source of a yellow vegetable" , "Central part of the maize ear" , "Bit of maize" .)