Secure saddle as horse shelters (5)
I believe the answer is:
leash
'secure' is the definition.
(thesaurus)
'saddle as horse shelters' is the wordplay.
'shelters' indicates a hidden word.
'LEASH' is hidden in the letters of 'saddle as horse'.
(Other definitions for leash that I've seen before include "Strap for holding a dog while walking" , "(Dog's) lead" , "Rope used to restrain an animal" , "Spanish city famous for swordmaking" , "Rope to control dog" .)