Empty-headed son ignored being spiteful (5)
I believe the answer is:
catty
'spiteful' is the definition.
(catty can mean spiteful or nasty)
'empty-headed son ignored' is the wordplay.
'empty-headed' becomes 'scatty' (I've seen this before).
'son' becomes 's' (genealogical abbreviation for son).
'ignored' is a deletion indicator.
'scatty' with 's' removed is 'CATTY'.
'being' acts as a link.
(Other definitions for catty that I've seen before include "Spiteful in feline way" , "Bitchy as a feline" , "Mean and spiteful" , "Malicious" , "Backbiting" .)