Dash south with mad character. . . (7)
I believe the answer is:
shatter
'dash' is the definition.
(thesaurus)
'south with mad character' is the wordplay.
'south' becomes 's' (abbreviation).
'with' is a charade indicator (letters next to each other).
'mad character' becomes 'hatter' (the mad hatter from Alice in Wonderland).
's'+'hatter'='SHATTER'
(Other definitions for shatter that I've seen before include "Break the minister into little pieces" , "Break suddenly" , "Completely upset" , "Break into fragments" , "total" .)