Stranger at back of band? (7)
I believe the answer is:
drummer
'stranger at back of band?' is the definition.
I can't judge whether this definition defines the answer.
'stranger at back of band?' is the wordplay.
'stranger' becomes 'rummer' (rum can mean strange).
'at' is a charade indicator (letters next to each other) (I've seen this in other clues).
'back of' suggests the final letters.
The final letter of 'band' is 'd'.
'rummer' put after 'd' is 'DRUMMER'.
(Other definitions for drummer that I've seen before include "player among the percussion" , "Musician" , "One using sticks" , "Someone who keeps 18 [RHYTHM]" , "Rich, say" .)