Poles wearing no vest without a break (7)
I believe the answer is:
nonstop
'without a break' is the definition.
(continuing without stopping)
'poles wearing no vest' is the wordplay.
'poles' becomes 'ns' (North and South poles).
'wearing' is an insertion indicator.
'vest' becomes 'top' (type of garment worn as a top).
'no'+'top'='notop'
'ns' inserted within 'notop' is 'NONSTOP'.
(Other definitions for nonstop that I've seen before include "Incessant" , "Going straight from A to B" , "done without interruption" , "Continuous, without pause" , "Constant" .)