Monster making one cautious — b*** hell! (9)
I believe the answer is:
charybdis
'monster' is the definition.
(I've seen this before)
'one cautious b hell' is the wordplay.
'one cautious' becomes 'chary' (I've seen this before).
'hell' becomes 'dis' (underworld in classical mythology).
'chary'+'b'+'dis'='CHARYBDIS'
'making' is the link.
(Other definitions for charybdis that I've seen before include "Mythical whirlpool" , "Scylla's counterpart" , "monster" , "Whirlpool, across from 14" , "Whirlpool opposite Scylla" .)