Unscrupulous businessman with cattle herder (6)
I believe the answer is:
cowboy
'herder' is the definition.
(thesaurus)
'unscrupulous businessman with cattle' is the wordplay.
'unscrupulous businessman' becomes 'boy' (I can't explain this - if you can you should give a lot more credence to this answer).
'with' is a charade indicator (letters next to each other).
'cattle' becomes 'cow' (cow is a kind of cattle).
'boy' after 'cow' is 'COWBOY'.
Can you help me to learn more?
(Other definitions for cowboy that I've seen before include "Artisan doing shoddy work" , "Wild West character" , "Hired hand for cattle-ranch" , "Hired hand who tended cattle in the old west" , "Mounted herdsman" .)