Oil beginning to exude under wrecked scooter (8)
I believe the answer is:
creosote
'oil' is the definition.
(thesaurus)
'beginning to exude under wrecked scooter' is the wordplay.
'beginning to' indicates taking the first letters.
'under' says to put letters next to each other.
'wrecked' indicates an anagram.
The initial letter of 'exude' is 'e'.
'scooter' is an anagram of 'creosot'.
'e' put after 'creosot' is 'CREOSOTE'.
(Other definitions for creosote that I've seen before include "Dark oily liquid, preservative for wood" , "Oily excretion" , "'Dark oily liquid, preserves wood (8)'" , "Oily liquid obtained from tar" , "Wood-preserving oil" .)