The gold rings are different (5)
I believe the answer is:
other
'different' is the definition.
(similar in meaning)
'the gold rings' is the wordplay.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'rings' means one lot of letters goes inside another (some letters are ringed or contained by others).
'the' going into 'or' is 'OTHER'.
'are' acts as a link.
(Other definitions for other that I've seen before include "Remaining" , "Alternative of two" , "Throe (anag)" , "Different; alternate" , "Second" .)