Knight, a bit dodgy, giving off bad smell (5)
I believe the answer is:
niffy
'bad smell' is the definition.
Both the definition and answer are adjectives. Perhaps there's an association between them I don't understand?
'knight a bit dodgy giving' is the wordplay.
'knight' becomes 'n' (chess abbreviation).
'a bit dodgy giving' becomes 'iffy' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'n'+'iffy'='NIFFY'
'off' is the link.
Can you help me to learn more?
(Other definitions for niffy that I've seen before include "stink" , "Smelly (slang)" , "Smelly (sl.)" .)