Counter odd note about king (5)
I believe the answer is:
token
'counter' is the definition.
(I've seen this before)
'odd note about king' is the wordplay.
'odd' is an anagram indicator.
'about' means one lot of letters goes inside another.
'king' becomes 'K' (chess abbreviation).
'note' is an anagram of 'toen'.
'toen' going around 'k' is 'TOKEN'.
(Other definitions for token that I've seen before include "Nominal, slight" , "Disc used as money or a gift card" , "signal" , "Sign, maybe substitute for the real thing" , "Gift voucher - symbol" .)