Allegedly, Trump's vulgar (5)
I believe the answer is:
rough
'vulgar' is the definition.
(thesaurus)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for rough that I've seen before include "scratchy" , "Hard - coarse - inexact" , "The long grass on the golf course" , "Unpolished" , "general" .)