In business, one can be tarred! (6)
I believe the answer is:
trader
'in business one' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'can be tarred' is the wordplay.
'can be' indicates an anagram.
'tarred' anagrammed gives 'TRADER'.
Can you help me to learn more?
(Other definitions for trader that I've seen before include "One selling" , "Merchant ship; dealer" , "One buys and sells" , "Retard (anag.)" , "He buys and sells goods" .)