English company in Knock shows propriety (7)
I believe the answer is:
decorum
'propriety' is the definition.
(I know that decorum is a type of propriety)
'english company in knock' is the wordplay.
'english' becomes 'E' (abbreviation).
'company' becomes 'co' (abbreviation).
'in' indicates putting letters inside.
'knock' becomes 'drum' (knock can mean to rap or drum against something).
'e'+'co'='eco'
'eco' inserted into 'drum' is 'DECORUM'.
'shows' is the link.
(Other definitions for decorum that I've seen before include "This is becoming" , "Correctness or dignity of behaviour" , "good behaviour" , "Propriety in manners and conduct" , "Seemly behaviour" .)