Large and dreadful — but not forbidden (6)
I believe the answer is:
lawful
'not forbidden' is the definition.
The answer and definition are not the same part of speech. However, adjectives and past participle verbs can sometimes mean the same thing.
'large and dreadful' is the wordplay.
'large' becomes 'L' (eg in clothes sizes).
'and' is a charade indicator (letters next to each other).
'dreadful' becomes 'awful' (synonyms).
'l'+'awful'='LAWFUL'
'but' acts as a link.
Can you help me to learn more?
(Other definitions for lawful that I've seen before include "Legally permitted" , "Legally permissible" , "Legal" , "Right!" , "Licit" .)