Doctor acquires green furnishings (5)
I believe the answer is:
decor
'furnishings' is the definition.
(decoration of a room)
'doctor acquires green' is the wordplay.
'doctor' becomes 'Dr' (abbreviation).
'acquires' means one lot of letters goes inside another.
'green' becomes 'eco' (eco-friendly).
'dr' going around 'eco' is 'DECOR'.
(Other definitions for decor that I've seen before include "(Room) design" , "Choice of colour" , "Colour-scheme etc of a room" , "stage background" , "Embellishment of a room" .)