Current run taken by Scottish philosopher (8)
I believe the answer is:
millrace
'current' is the definition.
(thesaurus)
'run taken by scottish philosopher' is the wordplay.
'run' becomes 'race' (synonyms).
'taken by' is a charade indicator (letters next to each other).
'scottish philosopher' becomes 'Mill' (economist and philosopher John Stuart Mill).
'race' put after 'mill' is 'MILLRACE'.
(Other definitions for millrace that I've seen before include "current providing power" , "Flow of water" , "Channel leading to water wheel" , "Channel for water driving wheel" , "Channel for the water current that turns a wheel" .)