Nobleman keeping nothing in outhouse (5)
I believe the answer is:
baron
'nobleman' is the definition.
(baron is a kind of nobleman)
'nothing in outhouse' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'in' indicates putting letters inside.
'outhouse' becomes 'barn' (I've seen this before).
'o' inserted into 'barn' is 'BARON'.
'keeping' acts as a link.
(Other definitions for baron that I've seen before include "Title of rank" , "An English lord or a magnate" , "Husband" , "Powerful financier" , "Lowest title of peerage" .)