Get snug (6)
I believe the answer is:
'get snug' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for nestle that I've seen before include "Huddle (together)" , "Cuddle into soft place" , "Be snug as a baby bird" , "Cuddle or snuggle up" , "Get cosy" .)