Wise man or old woman with a musical cat (5)
I believe the answer is:
magus
'wise man' is the definition.
(I've seen this before)
'old woman with a musical cat' is the wordplay.
'old woman' becomes 'ma' (I've seen this in other clues).
'with' is a charade indicator (letters next to each other).
'a musical cat' becomes 'gus' (character from the musical Cats).
'ma'+'gus'='MAGUS'
'or' is the link.
(Other definitions for magus that I've seen before include "Gift-bearing Wise Man" , "Sorcerer" , "astrologer" , "Magician, wise man" , "Wizard" .)