Hard to read, a decent code should be (14)
I believe the answer is:
indecipherable
'hard' is the definition.
Both the answer and definition are adjectives. Perhaps there's a link between them I don't understand?
'read a decent code should be' is the wordplay.
I cannot quite understand how this works, but
'read' could be 'decipher' (deciphering is a kind of reading) and 'decipher' is present in the answer.
'a' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'to' acts as a link.
Can you help me to learn more?
(Another definition for indecipherable that I've seen is " not good for readers".)