Pinch the nose (6)
I believe the answer is:
snitch
I believe this is a double definition.
'pinch' is the first definition.
(thesaurus)
'the nose' is the second definition.
(thesaurus)
(Other definitions for snitch that I've seen before include "Police informer" , "Grass" , "I'm telling!" , "Inform on someone in slangy way" , "Steal; inform (on someone)" .)