Ready to have a piece of furniture (4)
I believe the answer is:
seat
'piece of furniture' is the definition.
(seat is a kind of piece of furniture)
'ready to have a' is the wordplay.
'ready' becomes 'set' (set can mean ready or prepared).
'to have' is an insertion indicator.
'set' going around 'a' is 'SEAT'.
(Other definitions for seat that I've seen before include "MP's place in parliament" , "Somewhere to sit" , "Chair - bottom" , "Eg, chair, stool" , "Sitting place" .)