Feign sleep (4,6)
I believe the answer is:
play possum
'feign sleep' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for play possum that I've seen before include "Feign death" , "give lifeless performance" , "Feign unawareness" , "Pretend to have kicked the bucket" , "Fake death or sleep" .)