Dread faux pas by leader of Tories (6)
I believe the answer is:
terror
'dread' is the definition.
(synonyms)
'faux pas by leader of tories' is the wordplay.
'faux pas' becomes 'error' (I've seen this before).
'by' means one lot of letters go next to another.
'leader of' suggests taking the first letters.
The first letter of 'tories' is 't'.
'error' after 't' is 'TERROR'.
(Other definitions for terror that I've seen before include "Alarm" , "Paralysing fear" , "Ovewhelming fear" , "Extreme fear of dread" , "Troublesome child" .)