Nobleman suffering from prohibition? (5)

I believe the answer is:

baron

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'nobleman' is the definition.
(baron is a kind of nobleman)

I don't understand how the remainder of the clue works.

(Other definitions for baron that I've seen before include "British peer of the lowest rank" , "Lowest rank of British peerage" , "A born nobleman" , "Member of the nobility" , "Born a (anagram) - powerful man of business" .)

I've seen this clue in The Irish Independent.

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