Reformed buccaneer having run away to square sins? (7)
I believe the answer is:
expiate
'to square sins?' is the definition.
'reformed buccaneer having run away' is the wordplay.
I cannot quite understand how this works, but
'reformed' could be 'ex' and 'ex' is found in the answer.
'away' could be 'a' (abbreviation as used in sports fixtures) and 'a' is present in the answer.
This may be the basis of clue (or it may be nonsense).
(Other definitions for expiate that I've seen before include "right?" , "Do penance, make amends" , "make atonement" , "Make amends for wrongdoing" , "Of sin, make amends for" .)