Change part of ’orse’s equipment (5)
I believe the answer is:
alter
'change' is the definition.
(I know that change can be written as alter)
'part of 'orse's equipment' is the wordplay.
I cannot really see how this works, but
'part' could be 'te' (te is a kind of part) and 'te' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for alter that I've seen before include "convert" , "Metamorphose" , "Change, modify" , "Adapt" , "Change or adjust" .)