Rector has confused band (9)
I believe the answer is:
orchestra
'band' is the definition.
(I've seen this before)
'rector has confused' is the wordplay.
'confused' is an anagram indicator.
'rector'+'has'='rectorhas'
'rectorhas' is an anagram of 'ORCHESTRA'.
(Other definitions for orchestra that I've seen before include "many players" , "An assembly of musicians with various instruments" , "Big band" , "Large group of instrumentalists" , "Musicians, maybe in theatre" .)