Silly person's accommodation in a state (5)
I believe the answer is:
'silly person's' is the definition.
(a ninny is a foolish person)
'accommodation in a state' is the wordplay.
'accommodation' becomes 'inn' (an inn accommodates guests).
'in' indicates putting letters inside.
'a state' becomes 'ny' (short for New York).
'inn' going into 'ny' is 'NINNY'.
(Other definitions for ninny that I've seen before include "not a wise man" , "dope" , "Stupid foolish person" , "Fool" , "Simpleton" .)