Horrid smell (6)
I believe the answer is:
stench
'horrid smell' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for stench that I've seen before include "Evidence of corruption" , "Dreadful pong" , "A really vile smell" , "Unpleasant odour" , "Foul odour" .)