Peer keeping nothing in farm building (5)
I believe the answer is:
baron
'peer' is the definition.
(baron is a kind of peer)
'nothing in farm building' is the wordplay.
'nothing' becomes 'O' (looks like zero - 0).
'in' means one lot of letters goes inside another.
'farm building' becomes 'barn' (barn is a kind of farm building).
'o' going into 'barn' is 'BARON'.
'keeping' is the link.
(Other definitions for baron that I've seen before include "Member of the nobility" , "Title of rank" , "captain of industry" , "Minor peer" , "Lowest title of peerage" .)