Early car company's enthusiasm at rising appeal (7)
I believe the answer is:
bugatti
'early car' is the definition.
'bugatti' can be an answer for 'car' (I have seen 'Vintage car' mean 'bugatti' so perhaps 'car' could also mean 'bugatti'). I'm not certain of the 'early' bit.
'company's enthusiasm at rising appeal' is the wordplay.
'company's enthusiasm' becomes 'bug' (I can't explain this - if you can you should believe this answer much more).
'rising' says the letters should be written in reverse (in a down clue, letters go up).
'appeal' becomes 'it' ('it' can mean something attractive or appealing).
'it' back-to-front is 'ti'.
'bug'+'at'+'ti'='BUGATTI'
Can you help me to learn more?
(Other definitions for bugatti that I've seen before include "classic racing car" , "Classic French car firm" , "Early Italian car manufacturer" , "(Of horse) being used for breeding" , "Vintage car" .)