Empty offices filled with unfinished modern units? (4)
I believe the answer is:
ones
'units?' is the definition.
(I know this)
'empty offices filled with unfinished modern' is the wordplay.
'empty offices' becomes 'os' (I can't explain this - if you can you should give a lot more credence to this answer).
'filled with' means one lot of letters goes inside another.
'unfinished' means to remove the last letter.
'modern' becomes 'new' (associated in meaning).
'new' with its final letter taken off is 'ne'.
'os' enclosing 'ne' is 'ONES'.
Can you help me to learn more?
(Other definitions for ones that I've seen before include "Aces" , "(Of ship) returning to port of origin" , "Units" , "Individuals" , "Singles" .)