Point — nasty thorn! (5)
I believe the answer is:
north
'point' is the definition.
(north is a kind of point)
'nasty thorn' is the wordplay.
'nasty' indicates anagramming the letters.
'thorn' anagrammed gives 'NORTH'.
(Other definitions for north that I've seen before include "British leader" , "Former statesman" , "Compass bearing" , "Boreas was the god of the - wind" , "Direction of Edinburgh from Cardiff" .)