Noblemen excluding old Poles (6)
I believe the answer is:
barons
'noblemen' is the definition.
(baron is a kind of nobleman)
'excluding old poles' is the wordplay.
'excluding' becomes 'bar' (bar can mean excluding or except).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'poles' becomes 'ns' (North and South poles).
'bar'+'o'+'ns'='BARONS'
(Other definitions for barons that I've seen before include "Lords" , "Low-ranking British peers" , "No bars for the British peers" .)