It would be prudent to read the letters aloud (4)
I believe the answer is:
wise
'it would be prudent to read the letters aloud' is the definition.
The definition suggests a singular noun which matches the answer.
'it' is the wordplay.
I cannot really understand how this works, but
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found in the answer.
The remaining letters 'wis' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for wise that I've seen before include "comedian" , "Having good judgment or common sense" , "Clever" , "Morecambe partner" , "Sapient" .)