Amiable sound of horse, big and sturdy, circling ring (11)
I believe the answer is:
neighbourly
'amiable' is the definition.
(thesaurus)
'sound of horse big and sturdy circling ring' is the wordplay.
'sound of horse' becomes 'neigh' (I've seen this before).
'big and sturdy' becomes 'burly' (I've seen this before).
'circling' indicates putting letters inside (circling can mean going around or containing).
'ring' becomes 'o'.
'burly' going around 'o' is 'bourly'.
'neigh'+'bourly'='NEIGHBOURLY'
(Other definitions for neighbourly that I've seen before include "Friendly to those living near by" , "kind to one on adjoining territory?" , "maintaining friendly relations" , "Friendly, social" .)