First of properties kept back and maintained (9)
I believe the answer is:
preserved
'maintained' is the definition.
(similar in meaning)
'first of properties kept back' is the wordplay.
'first of properties' becomes 'p' (1st letter of 'properties').
'kept back' becomes 'reserved' (to reserve an item is to keep it back for someone).
'p'+'reserved'='PRESERVED'
'and' is the link.
(Other definitions for preserved that I've seen before include "Maintained in an unaltered condition" , "Prevented from decay" , "Prevented from decaying or spoiling" , "Kept safe from harm" , "Kept in an unaltered condition" .)