One Piece serial ultimately broadcast for a long time (9)

'a long time' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see a link between them that I can't see?

'one piece serial ultimately broadcast' is the wordplay.
'ultimately' says to take the final letters.
'broadcast' is an anagram indicator (letters scattered or cast around).
The final letter of 'serial' is 'l'.
'one'+'piece'+'l'='onepiecel'
'onepiecel' anagrammed gives 'PLEIOCENE'.

'for' is the link.

Can you help me to learn more?