A bit of a pungent odour will cause a fuss (4)
I believe the answer is:
todo
'fuss' is the definition.
(I've seen this in other clues)
'a bit of a pungent odour will' is the wordplay.
'a bit of' says the answer is hidden in the clue.
'TODO' is hidden within 'pungent odour will'.
'cause a' acts as a link.
(Other definitions for todo that I've seen before include "List that plans" , "disturbance" .)