Shape of some office desks (3)
I believe the answer is:
tee
'shape of some office desks' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tee that I've seen before include "Peg for golfer" , "Golf starting point" , "'Drive off it, half-laughing (3)'" , "Starting place on the golf course" , "Golfing item" .)