Bottleneck (5)
I believe this is a double definition.
'bottle' is the first definition.
(both can mean courage)
'neck' is the second definition.
(both can mean attitude or insolence)
(Other definitions for nerve that I've seen before include "Impulse transmitter - bottle" , "Sensation transmitter" , "Sauce" , "Bodily fibre carrying sensation" , "Sensory organ; bottle" .)
'bottleneck' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for snarl that I've seen before include "Bare teeth and growl" , "Entangle wool - show displeasure" , "Growl aggressively" , "Tangle; growl" , "Growl viciously" .)