Being messed about with hurt aged relative (8)
I believe the answer is:
daughter
'relative' is the definition.
(daughter is a kind of relative)
'being messed about with hurt aged' is the wordplay.
'being messed about' indicates anagramming the letters.
'with' says to put letters next to each other.
'hurt' put next to 'aged' is 'hurtaged'.
'hurtaged' with letters rearranged gives 'DAUGHTER'.
(Other definitions for daughter that I've seen before include "The guard (anag.)" , "Female descendant" , "Girl" , "Dug earth (anag.)" , "Female child" .)