Treasured singer hides arrangement (9)
I believe the answer is:
cherished
'treasured' is the definition.
(synonyms)
'singer hides arrangement' is the wordplay.
'singer' becomes 'cher' (American singer).
'arrangement' indicates an anagram.
'hides' anagrammed gives 'ished'.
'cher'+'ished'='CHERISHED'
(Other definitions for cherished that I've seen before include "clung to" , "Held dear" , "Precious" , "Was protective" , "Lovingly cared for" .)