This will hold a great deal of food for the horse (7)
I believe the answer is:
charger
'horse' is the definition.
(charger is a type of horse)
'this will hold a great deal of food' is the wordplay.
I cannot really understand how this works, but
'a' is found in the answer.
'great' could be 'g' (abbreviation in place names) and 'g' is located in the answer.
'food' could be 'e' (E is an example) and 'e' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'for the' is the link.
Can you help me to learn more?
(Other definitions for charger that I've seen before include "Cavalry horse - used on battery" , "needed for battery" , "A large dish or a cavalry horse" , "I expect payment" , "He doesn't mean it to be a gift" .)