Barker's call for a cigarette (4-2)
I believe the answer is:
roll up
'cigarette' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for roll up that I've seen before include "Home-made cigarette" , "Appear" , "smoke" , "Fairground barker's exhortation" , "Arrive -- handmade cigarette (4,2;4-2)" .)