Crossword Genius

Distant object is an old coin (8)

Ross

I believe the answer is:

farthing

Here is my best explanation:

'an old coin' is the definition.
(I've seen this before)

'distant object' is the wordplay.
'distant' becomes 'far' (synonyms).
'object' becomes 'thing'.
'far'+'thing'='FARTHING'

'is' acts as a link.