Horse gets food with nothing on top (7)
I believe the answer is:
piebald
'horse' is the definition.
'food with nothing on top' is the wordplay.
'food' becomes 'pie' (pie is a kind of food).
'with nothing on top' becomes 'bald' (I can't explain this - if you can you should give a lot more credence to this answer).
'pie'+'bald'='PIEBALD'
'gets' is the link.
Can you help me to learn more?
(Other definitions for piebald that I've seen before include "Of horse, with patches of white and dark colour" , "Two-toned" , "(Of an animal) marked in two different colours" , "Marked in two different colours, especially black and white" , "(Of horse) black and white in patches" .)