Stop start?
'stop start?' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for non that I've seen before include "- - -stick" , "Combining form meaning not" , "Negative French word" , "Prefixed negation of a word" , "Prefix meaning not or none" .)
(Other definitions for short that I've seen before include "Limited in duration" , "Cause to blow a fuse" , "Of small duration" , "Terse; in insufficient supply" , "Neat" .)