No food for cool cats (3,4)
I believe the answer is:
hot dogs
'no' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'food for cool cats' is the wordplay.
'food' becomes 'hot dog' (hot dog is a food product).
'for' means one lot of letters go next to another.
'cool cats' becomes 's' (I can't justify this - if you can you should give a lot more credence to this answer).
'hotdog'+'s'='HOT-DOGS'
Can you help me to learn more?
(Other definitions for hot dogs that I've seen before include "performs tricks in New York" , "Fast food items - sweaty hounds?" .)