Continuously (7)
(Other definitions for nonstop that I've seen before include "(Of a flight) direct" , "Without halting" , "done without interruption" , "Going straight from A to B" , "Never-ending" .)
'continuously' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for onend that I've seen before include "Continuously" , "erect" .)