Haughty letters to a public relations officer (5)
I believe the answer is:
proud
'haughty' is the definition.
(similar in meaning)
'letters to a public relations officer' is the wordplay.
'letters' becomes 'ud' (I can't explain this - if you can you should give a lot more credence to this answer).
'to a' is a charade indicator (letters next to each other) (I've seen this in other clues).
'public relations officer' becomes 'pro'.
'ud' put after 'pro' is 'PROUD'.
Can you help me to learn more?
(Other definitions for proud that I've seen before include "Haughty; projecting a little" , "Stuck-up" , "Self-satisfied - stately - protruding" , "Arrogant - sticking out" , "Boastful" .)