Pale sort of petition (4)
I believe the answer is:
plea
'petition' is the definition.
(petition can mean to plea or beg)
'pale sort' is the wordplay.
'sort' is an anagram indicator.
'pale' is an anagram of 'PLEA'.
'of' acts as a link.
(Other definitions for plea that I've seen before include "suit" , "Dispute" , "Earnest entreaty" , "Guilty perhaps" , "Appeal - with bargaining?" .)