Stop working for nobleman (5)
I believe the answer is:
baron
'nobleman' is the definition.
(baron is a kind of nobleman)
'stop working' is the wordplay.
'stop' becomes 'bar' (I've seen this before**).
'working' becomes 'on'.
'bar'+'on'='BARON'
'for' acts as a link.
(Other definitions for baron that I've seen before include "Born a (anagram) - powerful man of business" , "Lowest rank of British nobility" , "An English lord or a magnate" , "Husband" , "powerful man owning lots of dailies?" .)