King to object to gear (3)
I believe the answer is:
kit
'to gear' is the definition.
(kit is a kind of gear)
'king to object' is the wordplay.
'king' becomes 'K' (abbreviation for king in chess).
'to object' becomes 'it' (pronoun for an inanimate object).
'k'+'it'='KIT'
(Other definitions for kit that I've seen before include "Colours are visible on such" , "Young beaver" , "Set of equipment, perhaps for first-aid" , "Specialised clothing or set of parts for assembly" , "Equipment; young ferret" .)