Part of issue the guard sorted (8)
I believe the answer is:
daughter
'part of issue' is the definition.
(issue can mean someone's offspring)
'the guard sorted' is the wordplay.
'sorted' indicates anagramming the letters.
'the'+'guard'='theguard'
'theguard' anagrammed gives 'DAUGHTER'.
(Other definitions for daughter that I've seen before include "Dug earth (anag.)" , "Girl" , "The guard (anag.)" , "Female child" , "Relation" .)