Horses given hitch with head pushed right back (4)
I believe the answer is:
nags
'horses' is the definition.
(nag is a kind of horse)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for nags that I've seen before include "Constantly reproaches and complains" , "Scolds continually" , "Pesters" , "Worries; horses" , "Constantly finds fault" .)