A room containing receptacles in the centre for bonsai, say (3,4)
I believe the answer is:
art form
'bonsai say' is the definition.
(I know that bonsai is a art form)
'a room containing receptacles in the centre for' is the wordplay.
'room' becomes 'rm' (abbreviation for room).
'containing' means one lot of letters goes inside another.
'in the centre' says to take the centre.
The centre of 'receptacles' is 't'.
't'+'for'='tfor'
'rm' placed around 'tfor' is 'rtform'.
'a'+'rtform'='ART FORM'
(Other definitions for art form that I've seen before include "novel!" , "The sonata, for example" , "Traditional medium of creative expression" , "Creative genre" , "Writing or painting, for example" .)