Deep regret about code creator (7)
I believe the answer is:
remorse
'deep regret' is the definition.
(I've seen this before)
'about code creator' is the wordplay.
'about' becomes 're' ('re' means regarding or about).
'code creator' becomes 'Morse' (Samuel Morse, inventor of Morse code).
're'+'morse'='REMORSE'
(Other definitions for remorse that I've seen before include "Regret for wrong" , "Guilt for a wrong deed" , "display of conscience" , "A feeling of deep regret" , "Pity" .)