Emergency set-up, product that sells quickly (7)
I believe the answer is:
hotline
'emergency set-up' is the definition.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for hotline that I've seen before include "Emergency blower" , "Direct phone link" , "Direct telephone link between two officials" , "Important number to call" , "Former direct phone line between the White House and the Kremlin" .)