Delighted to stock electric vehicle they promoted (8)
I believe the answer is:
elevated
'promoted' is the definition.
('elevate' can be a synonym of 'promote')
'delighted to stock electric vehicle they' is the wordplay.
'delighted' becomes 'elated' (I've seen this before).
'to stock' means one lot of letters goes inside another (some letters contain or stock others).
'electric vehicle they' becomes 'ev' (I can't justify this - if you can you should believe this answer much more).
'elated' placed around 'ev' is 'ELEVATED'.
Can you help me to learn more?
(Other definitions for elevated that I've seen before include "in high place" , "Heightened" , "by such an American railway?" , "of high status" , "Exalted; lifted" .)