Snare: section springing back (4)
I believe the answer is:
trap
'snare' is the definition.
('trap' can be a synonym of 'snare')
I cannot understand how the rest of the clue works.
(Other definitions for trap that I've seen before include "that may catch a speeding motorist" , "Trick" , "one would be ill advised to enter?" , "Kisser" , "that can let an actor down" .)