Object is almost reserved (5)
I believe the answer is:
demur
'object' is the definition.
(to demur is to object to something)
'almost reserved' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'reserved' becomes 'demure' (I've seen this in another clue).
'demure' with its final letter taken off is 'DEMUR'.
'is' is the link.
(Other definitions for demur that I've seen before include "Waver" , "Raise objections" , "Hesitation" , "Raise scruples" , "Protest mildly, show reluctance" .)