Midday break (3)
I believe the answer is:
nap
'midday break' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for nap that I've seen before include "one akin to whist" , "Racing tip that professes to be a certainty" , "Little sleep" , "Sleep - card game - fibres on a snooker table" , "Snatch forty winks" .)