Say, are you home before midnight, feeling sorry? (5)
I believe the answer is:
'feeling sorry?' is the definition.
(I've seen this before)
'say are you home before midnight' is the wordplay.
'say are' becomes 'r' (r sounds like are).
'you' becomes 'u' (commonly used in online communication).
'home' becomes 'in' ('he's home' can mean 'he's in').
'before' says to put letters next to each other.
'midnight' becomes 'g' (the middle letter in 'night').
(Other definitions for ruing that I've seen before include "Feeling sorry for" , "full of remorse?" , "Having second thoughts" , "Feeling bad" , "Bitterly regretting" .)