Dahl hid a wrongly written pretentious speech (3-2-3)
I believe the answer is:
lah-di-dah
'written pretentious speech' is the definition.
The definition suggests a singular noun which matches the answer.
'dahl hid a wrongly' is the wordplay.
'wrongly' indicates an anagram.
'dahl'+'hid'+'a'='dahlhida'
'dahlhida' is an anagram of 'LAH-DI-DAH'.
Can you help me to learn more?
(Other definitions for lah-di-dah that I've seen before include "Affectedly genteel, highfalutin" , "Affectedly posh" , "with a superior attitude?" , "Pretentiously refined, affected in speech and manners" , "Pretentious, snobbish (colloq.)" .)