A din we may hear is irritating (6)
I believe the answer is:
annoys
'we may hear is irritating' is the definition.
I can't judge whether this defines the answer.
'a din' is the wordplay.
'a' becomes 'an'.
'din' becomes 'noys' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'an'+'noys'='ANNOYS'
Can you help me to learn more?
(Other definitions for annoys that I've seen before include "Causes irritation" , "Nettles" , "Irritates, vexes" , "Narks" , "'Irritates, irks (6)'" .)