Snuck (5)
I believe the answer is:
crept
'snuck' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for crept that I've seen before include "cringed" , "Moved slowly with stealth and caution" , "Moved slowly and carefully" , "Went stealthily or furtively" , "was obsequious" .)