Nothing in routes that arouses pity (6)
I believe the answer is:
pathos
'that arouses pity' is the definition.
(pathos evokes pity)
'nothing in routes' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'in' means one lot of letters goes inside another.
'routes' becomes 'paths' ('path' can be a synonym of 'route').
'o' put within 'paths' is 'PATHOS'.
(Other definitions for pathos that I've seen before include "Something evoking pity" , "Quality with power to provoke pity or sadness" , "feeling of pity" , "Quality that arouses sympathy" , "Quality eliciting pity and sympathy" .)