Plastic as central, going some way back? (9)
I believe the answer is:
ancestral
'going some way back?' is the definition.
(going back to one's ancestors)
'plastic as central' is the wordplay.
'plastic' is an anagram indicator (plastic can mean easily moulded).
'as'+'central'='ascentral'
'ascentral' with letters rearranged gives 'ANCESTRAL'.
(Other definitions for ancestral that I've seen before include "handed down by family" , "To do with forebears, say stately home" , "To do with forebears from Lancaster" , "of predecessors" , "description of voices prophesying war?" .)