Condo, for one (4)
I believe the answer is:
This clue is a double definition.
'condo' is the first definition.
(I've seen this in another clue)
'for one' is the second definition.
(Other definitions for unit that I've seen before include "hospital department" , "Standard for measuring" , "A considerable number of soldiers" , "Individual thing, single and complete" , "Building block - small military force" .)