Turn down release by Queen (6)
I believe the answer is:
reject
'turn down' is the definition.
(I know that turn down can be written as reject)
'release by queen' is the wordplay.
'release' becomes 'eject' (synonyms).
'by' says to put letters next to each other.
'queen' becomes 'r' (abbreviation for regina, e.g. in ER ).
'eject' after 'r' is 'REJECT'.
(Other definitions for reject that I've seen before include "Refuse to accept, spurn" , "Dismiss as inadequate" , "Refuse as inadequate or unworthy" , "Refuse to accept, send back" , "Refuse to accept or react against" .)