Pale sort of request (4)
I believe the answer is:
plea
'request' is the definition.
(plea is a kind of request)
'pale sort' is the wordplay.
'sort' indicates an anagram.
'pale' anagrammed gives 'PLEA'.
'of' is the link.
(Other definitions for plea that I've seen before include "Guilty perhaps" , "Excuse - pretext" , "suit" , "Leap (anag.)" , "Appeal - with bargaining?" .)