It arouses pity giving power to musketeer (6)
I believe the answer is:
pathos
'it arouses pity' is the definition.
(I've seen this before)
'giving power to musketeer' is the wordplay.
'giving' means one lot of letters go next to another.
'power' becomes 'p'.
'to musketeer' becomes 'athos' (I've seen this before).
'p'+'athos' is 'PATHOS'.
(Other definitions for pathos that I've seen before include "Tragic air" , "Quality of attracting pity" , "feeling of pity" , "Quality arousing pity" , "A quality that arouses pity or sorrow" .)