Shame about a diver's descent (9)
I believe the answer is:
paternity
'descent' is the definition.
(thesaurus)
'shame about a diver's' is the wordplay.
'shame' becomes 'pity' (synonyms).
'about' is an insertion indicator.
'diver' becomes 'tern' (type of diving bird).
'a'+'tern'='atern'
'pity' enclosing 'atern' is 'PATERNITY'.
(Other definitions for paternity that I've seen before include "suit Mick Jagger would wear?" , "Fatherhood" .)