Some petrol derivatives of earlier origin (5)

I believe the answer is:

older

I'm a little stuck... Click here to teach me more about this clue!

'earlier origin' is the definition.
I can't tell whether this definition defines the answer.

'some petrol derivatives of' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'OLDER' is hidden in the letters of 'petrol derivatives of'.

Can you help me to learn more?

(Other definitions for older that I've seen before include "more history" , "More aged" , "More senior" , "Less young" , "Getting on" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app