Miss second nap (4)
I believe the answer is:
skip
'miss' is the definition.
(skipping is a kind of missing)
'second nap' is the wordplay.
'second' becomes 's' (common abbreviation).
'nap' becomes 'kip' (I've seen this before**).
's'+'kip'='SKIP'
(Other definitions for skip that I've seen before include "item on a building site" , "Container used to dump rubbish" , "Omit - refuse container" , "Miss - waste container" , "Large container for rubbish" .)