Poor regrets are put up before deletion (7)
I believe the answer is:
erasure
'deletion' is the definition.
(I know that erasure is a type of deletion)
'poor regrets are put up before' is the wordplay.
'poor regrets' becomes 'sure' (I can't explain this - if you can you should give a lot more credence to this answer).
'put up' says the letters should be written in reverse.
'before' says to put letters next to each other.
'are' back-to-front is 'era'.
'sure' put after 'era' is 'ERASURE'.
Can you help me to learn more?
(Other definitions for erasure that I've seen before include "Wiping out - English pop duo" , "Deletion by an act of expunging" , "Obliteration - rare use (anag)" , "Obliteration of data" , "Process of rubbing out" .)