Groom heartlessly pinched gold rings (6)
I believe the answer is:
ostler
'groom' is the definition.
(synonyms)
'heartlessly pinched gold rings' is the wordplay.
'heartlessly' says to hollow out the word (remove centre letters).
'pinched' becomes 'stole' (pinch can mean to steal).
'gold' becomes 'or' ('or' is the heraldic name for gold).
'rings' is an insertion indicator (some letters are ringed or contained by others).
'stole' with its middle removed is 'stle'.
'stle' put inside 'or' is 'OSTLER'.
(Other definitions for ostler that I've seen before include "Horse attendant" , "Nags for me" , "Inn servant" , "Horse man" , "Inn attendant (hist.)" .)