Defeat object, removing king, but legal (5)
I believe the answer is:
licit
'legal' is the definition.
(similar in meaning)
'defeat object removing king' is the wordplay.
'defeat' becomes 'lick' (lick can mean to beat or defeat).
'object' becomes 'it' (pronoun for an inanimate object).
'removing' suggests deleting specific letters.
'king' becomes 'K' (chess abbreviation).
'lick'+'it'='lickit'
'lickit' with 'k' taken out is 'LICIT'.
'but' acts as a link.
(Other definitions for licit that I've seen before include "Permissible" , "Within the law" , "Not forbidden, lawful" , "Acceptable" , "not banned" .)