Stupid letter content (5)
I believe the answer is:
inane
'stupid' is the definition.
(I've seen this in another clue)
'letter content' is the wordplay.
I cannot really understand how this works, but
'letter' could be 'n' and 'n' is located in the answer.
'content' could be 'an' (AN is an example) and 'an' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for inane that I've seen before include "Silly, fatuous" , "Foolish, silly" , "Delirious" , "Daft" , "Unintelligent" .)