French number one gets fourth fault. Dreadful and illegal (8)
I believe the answer is:
unlawful
'illegal' is the definition.
(similar in meaning)
'french number one gets fourth fault dreadful' is the wordplay.
'french number' becomes 'un' (I can't justify this - if you can you should believe this answer much more).
'one gets' says to put letters next to each other.
'fourth fault' becomes 'l' (4th letter of 'fault').
'dreadful' becomes 'awful' (synonyms).
'un'+'l'+'awful'='UNLAWFUL'
'and' is the link.
Can you help me to learn more?
(Other definitions for unlawful that I've seen before include "Criminal" , "Illegal" , "Prohibited by legislation" , "Illicit" , "Not legally permitted" .)