Sketch room back-to-front (4)
I believe the answer is:
draw
'sketch' is the definition.
(I know that sketch is a more specific form of the action draw)
'room back-to-front' is the wordplay.
'room' becomes 'ward' (I've seen this before).
'back-to-front' is a reversal indicator.
'ward' back-to-front is 'DRAW'.
(Other definitions for draw that I've seen before include "Finish level" , "No-winner result" , "Attract; sketch" , "Even-scored game" , "Pull along; sketch" .)