Pardon a crack about bishop (7)
I believe the answer is:
absolve
'pardon' is the definition.
(thesaurus)
'a crack about bishop' is the wordplay.
'crack' becomes 'solve' (I've seen this before).
'about' means one lot of letters go next to another.
'bishop' becomes 'b' (abbreviation used in chess).
'solve' after 'b' is 'bsolve'.
'a'+'bsolve'='ABSOLVE'
(Other definitions for absolve that I've seen before include "Set free from guilt" , "Clear of blame or quilt" , "Declare to be free from blame" , "Exonerate" , "Declare (someone) guilt-free" .)