After surprise, I will abandon unfussy office layout (5,4)
I believe the answer is:
floor plan
'office layout' is the definition.
(floor plan is the layout of a room)
'after surprise i will abandon unfussy' is the wordplay.
'after' means one lot of letters go next to another.
'surprise' becomes 'floor' (flooring is a kind of surprising).
'will abandon' suggests deleting specific letters.
'unfussy' becomes 'plain' (unfussy can mean plain or simple).
'plain' with 'i' taken away is 'plan'.
'floor' next to 'plan' is 'FLOOR PLAN'.
(Other definitions for floor plan that I've seen before include "map" , "Design" .)