Chemist's room (3)
I believe the answer is:
lab
'chemist's room' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for lab that I've seen before include "Workplace for researcher" , "retriever" , "SECOND PART OF 15" , "Scientist's workroom" , "Scientific research space, in short" .)