Singers and band in rich arrangement (5)
I believe the answer is:
choir
'singers' is the definition.
(I've seen this before)
'band in rich arrangement' is the wordplay.
'band' becomes 'o' (I've seen this in other clues**).
'in' means one lot of letters goes inside another.
'arrangement' is an anagram indicator.
'rich' is an anagram of 'chir'.
'o' inserted within 'chir' is 'CHOIR'.
'and' is the link.
(Other definitions for choir that I've seen before include "Large group of singers" , "Religious chorus, perhaps" , "Singing group" , "Organised group of singers" , "Religious singers" .)