Play safe and sleep over (5,3)
I believe the answer is:
peter pan
'play' is the definition.
(I've seen this before)
'safe and sleep over' is the wordplay.
'safe' becomes 'peter' (slang term for a safe).
'and' says to put letters next to each other.
'sleep' becomes 'nap' (a nap is a short sleep).
'over' says the letters should be written in reverse.
'nap' in reverse letter order is 'pan'.
'peter'+'pan'='PETER PAN'
(Other definitions for peter pan that I've seen before include "Kind of collar for" , "Ever-youthful boy" , "Pantomime hero" , "JM Barrie character" , "Barrie's ageless youth" .)