Neat, if simple retro housing eccentric (6)
I believe the answer is:
misfit
'eccentric' is the definition.
(thesaurus)
'neat if simple retro housing' is the wordplay.
'housing' indicates a hidden word (part of the clue houses the answer).
'retro' says the letters should be written in reverse (retro is Latin for 'backwards').
'tifsim' is hidden within 'neat if simple'.
'tifsim' back-to-front is 'MISFIT'.
(Other definitions for misfit that I've seen before include "not a suitable one" , "Maverick, nonconformist" , "An unsuitable thing" , "Weirdo" , "One who is out of place" .)