Duet? Sit at different positions (9)
I believe the answer is:
attitudes
'positions' is the definition.
('attitude' can be a synonym of 'position')
'duet? sit at different' is the wordplay.
'different' is an anagram indicator.
'duet'+'sit'+'at'='duetsitat'
'duetsitat' is an anagram of 'ATTITUDES'.
(Other definitions for attitudes that I've seen before include "Positions, stances" , "feelings" , "Postures or opinions" , "Mental positions" , "Ways of thinking or feeling" .)