Guilty person’s regret about an own goal (5)
I believe the answer is:
rogue
'guilty person's regret about an own goal' is the definition.
I can't judge whether this definition defines the answer.
'regret about an own goal' is the wordplay.
'regret' becomes 'rue' ('rue' can be a synonym of 'regret').
'about' is an insertion indicator.
'an own goal' becomes 'og' (football abbreviation).
'rue' enclosing 'og' is 'ROGUE'.
Can you help me to learn more?
(Other definitions for rogue that I've seen before include "Old Greek" , "Diseased plant" , "Unprincipled man" , "Dishonest man" , "Scally" .)