Flexible cushion turned over in a piece of furniture (9)
I believe the answer is:
adaptable
'flexible' is the definition.
(similar in meaning)
'cushion turned over in a piece of furniture' is the wordplay.
'cushion' becomes 'pad' (to cushion something is to pad it).
'turned over' is a reversal indicator.
'in' is an insertion indicator.
'piece of furniture' becomes 'table' (table is a kind of piece of furniture).
'pad' reversed gives 'dap'.
'a'+'table'='atable'
'dap' put into 'atable' is 'ADAPTABLE'.
(Other definitions for adaptable that I've seen before include "Flexible, pliant" , "Good at fitting in to new circumstances" , "Able to adjust to new conditions" , "Good at fitting in to new situations" , "Able to adjust to circumstances" .)