A bit that's appropriate (7)
I believe the answer is:
snaffle
This clue is a double definition.
'a bit' is the first definition.
(type of bit used in horseriding)
'appropriate' is the second definition.
(I've seen this before)
'that's' acts as a link.
(Other definitions for snaffle that I've seen before include "A bit; steal (colloq.)" , "Horse's bit" , "Pinch" , "A bit; filch" , "Get hold of" .)