Saddle hybrid gelding must carry (5)
I believe the answer is:
ridge
'saddle' is the definition.
(I've seen this before)
'hybrid gelding must carry' is the wordplay.
'carry' indicates a hidden word (I've seen 'carries' mean this).
'RIDGE' is hidden in the letters of 'hybrid gelding must'.
(Other definitions for ridge that I've seen before include "Top of sloping roof" , "Narrow hilltop range" , "Raised strip of land" , "Line where two upward sloping surfaces meet" , "Raised edge" .)