Mutual respect shown in big town keeping order (6)
I believe the answer is:
'mutual respect' is the definition.
(I've seen this in another clue)
'big town keeping order' is the wordplay.
'big town' becomes 'city' (I've seen this before).
'keeping' indicates putting letters inside.
'order' becomes 'om' (Order of Merit).
'city' going around 'om' is 'COMITY'.
'shown in' is the link.
(Other definitions for comity that I've seen before include "Politeness", "Civilised state of affairs", "Courteousness", "Civility".)