Through Newcastle locally river finds course (5)
I believe the answer is:
troon
'course' is the definition.
(Royal Troon Golf Club, a golf course)
'through newcastle locally river' is the wordplay.
'through' indicates putting letters inside (some letters go through others).
'newcastle locally' becomes 'Toon' (local nickname for Newcastle).
'river' becomes 'r' (abbreviation for river).
'toon' placed around 'r' is 'TROON'.
'finds' acts as a link.
(Other definitions for troon that I've seen before include "West Scottish town with links" , "Open home" , "Scottish golf town" , "A royal Scottish golf club" , "Clyde port" .)