Kept quiet and reticent (9)
I believe the answer is:
preserved
'kept' is the definition.
(preserving is a kind of keeping)
'quiet and reticent' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano').
'and' means one lot of letters go next to another.
'reticent' becomes 'reserved' ('reserved' can be a synonym of 'reticent').
'p'+'reserved'='PRESERVED'
(Other definitions for preserved that I've seen before include "Prevented from decaying or spoiling" , "Prevented from decay" , "Maintained in an unaltered condition" , "Kept in an unaltered condition" , "Kept safe from harm" .)