The spell true polymorph ends when dispelled - even when the creature has been in their 'new' shape for hundreds of years. According to the Clone spell, any such polymorphed creature should still be able to use their (transformed) flesh as a component for this spell. If so, any Clone should grow as the spell suggests, as their present form / in four months.
Assume thereafter: the host creature goes to zero hit points. Thus the True Polymorph ends and they revert to their origin-creature (ibid). If this original-creature then dies, can their soul claim the Clone that they made whilst polymorphed?
Simple example: an orc is true polymorphed into a dragon. Dragon clones itself. Dragon-form 'dies' / reduced to zero & it turns back into orc. Orc then dies. Can this orc-soul (re) claim the clone-dragon body?