Nobleman puts duck in farm building (5)
I believe the answer is:
baron
'nobleman' is the definition.
(baron is a kind of nobleman)
'duck in farm building' is the wordplay.
'duck' becomes 'o' (resembles zero - 'duck' in cricket).
'in' means one lot of letters goes inside another.
'farm building' becomes 'barn' (barn is a kind of farm building).
'o' going within 'barn' is 'BARON'.
'puts' acts as a link.
(Other definitions for baron that I've seen before include "Minor nobleman" , "Title of rank" , "Powerful financier" , "Noble rank" , "powerful man owning lots of dailies?" .)