His band has an organ (6)
I believe the answer is:
oliver
'his' is the definition.
The answer and definition are not the same part of speech.
'band has an organ' is the wordplay.
'band' becomes 'o' (I've seen this in other clues).
'has' is a charade indicator (letters next to each other).
'an organ' becomes 'liver' (liver is a kind of organ).
'o'+'liver'='OLIVER'
(Other definitions for oliver that I've seen before include "Dickens boy named Twist" , "-- Reed, actor" , "stage show" , "The boy who wanted more" , "See 19" .)