Like our fellow countrymen’s mistake about short ceremony (7)
I believe the answer is:
british
'like our fellow countrymen's' is the definition.
I can't judge whether this definition defines the answer.
'mistake about short ceremony' is the wordplay.
'mistake' becomes 'bish' (informal term for an error).
'about' is an insertion indicator.
'short ceremony' becomes 'rit'.
'bish' going around 'rit' is 'BRITISH'.
Can you help me to learn more?
(Other definitions for british that I've seen before include "Like these old pieces" , "Is birth necessary for nationality? (7)" , "Rib this nationality badly" , "Children's game -- our national mascot?" , "race" .)