Does he fix the price of a horse? (7)
I believe the answer is:
charger
'a horse?' is the definition.
(charger is a type of horse)
'does he fix the price' is the wordplay.
I cannot really understand how this works, but
'price' could be 'charge' (I've seen this before) and 'charge' is found within the answer.
A single letter 'r' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'of' acts as a link.
Can you help me to learn more?
(Other definitions for charger that I've seen before include "A warhorse; a serving-dish" , "Big old plate" , "Type of platter" , "that would prevent loss of power?" , "What Richard III wanted, perhaps" .)