Why horn sound stood out like Japanese cars (7)
I believe the answer is:
toyotas
'japanese cars' is the definition.
I know nothing about this answer so I can't judge whether this works.
'why horn sound stood out' is the wordplay.
'why' becomes 'y'.
'horn sound' becomes 'toot' (I've seen this in another clue).
'stood' becomes 'as' (I can't explain this - if you can you should give a lot more credence to this answer).
'out' is an insertion indicator.
'toot'+'as'='tootas'
'y' placed within 'tootas' is 'TOYOTAS'.
'like' is the link.
Can you help me to learn more?
(Another definition for toyotas that I've seen is " Vehicles".)