Room in taxi on the left (5)
I believe the answer is:
cabin
'room' is the definition.
(I know that cabin is a type of compartment)
'in taxi on the left' is the wordplay.
'taxi' becomes 'cab' (synonyms).
'on the left' says to put letters next to each other (some letters go to the left of others).
'in' after 'cab' is 'CABIN'.
(Other definitions for cabin that I've seen before include "Marine digs" , "Wooden house" , "class at sea?" , "Building" , "Private room aboard" .)