Some in a park for short sleep (3)
I believe the answer is:
nap
'for short sleep' is the definition.
(a nap is a short sleep; 'short' indicates an abbreviation)
'some in a park' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'NAP' can be found hidden inside 'in a park'.
(Other definitions for nap that I've seen before include "Little sleep" , "one akin to whist" , "Sleep briefly" , "Raised surface of a fabric and short sleep" , "Short sleep on fuzzy fabric surface" .)