Like a bug in a rug (4)
I believe the answer is:
snug
'like a bug in a rug' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for snug that I've seen before include "Close fitting but comfortable" , "Cosy retreat" , "Comfortable -- small secluded room" , "Small bar in pub - warm and comfortable" , "He joined" .)