Lay outside on new hat (6)
I believe the answer is:
bonnet
'hat' is the definition.
(bonnet is a kind of hat)
'lay outside on new' is the wordplay.
'lay' becomes 'bet' (I've seen this in other clues).
'outside' means one lot of letters goes inside another.
'new' becomes 'n'.
'on'+'n'='onn'
'bet' enclosing 'onn' is 'BONNET'.
(Other definitions for bonnet that I've seen before include "Headgear -engine cover" , "Soft cap" , "Car part" , "Lady's hat musically associated with Easter" , "Old-fashioned woman's hat or a hinged cover over car engine" .)