Subsequent to second person using polite expression (5,3)
I believe the answer is:
after you
'polite expression' is the definition.
I don't know anything about this answer so I cannot tell whether this works.
'subsequent to second person' is the wordplay.
'subsequent to' becomes 'after' (I've seen this in another clue).
'second person' becomes 'you' (second person pronoun).
'after'+'you'='AFTER YOU'
'using' acts as a link.
Can you help me to learn more?
(Other definitions for after you that I've seen before include "I'll follow" , "Yielding statement" .)