Some unsold, Tim explains, being ancient (3-4)
I believe the answer is:
old-time
'ancient' is the definition.
(I've seen this in another clue)
'some unsold tim explains' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'OLD-TIME' is hidden within 'unsold tim explains'.
'being' acts as a link.
(Other definitions for old-time that I've seen before include "Relating to the past" , "Quaint" , "(E.g. dancing) in ancient style" .)