Distant object is an old coin (8)
I believe the answer is:
farthing
'an old coin' is the definition.
(I've seen this before)
'distant object' is the wordplay.
'distant' becomes 'far' (synonyms).
'object' becomes 'thing' (an object is a thing or item).
'far'+'thing'='FARTHING'
'is' is the link.
(Other definitions for farthing that I've seen before include "One quarter of an old penny: measure of land in old England" , "Old quarter of a penny is a remote object" , "once of minimal value" , "Smallest coin once" , "Old piece" .)