Debate is about what costs NHS billions (8)
I believe the answer is:
diabetes
'what costs nhs billions' is the definition.
I can't tell whether this definition defines the answer.
'debate is about' is the wordplay.
'about' is an anagram indicator.
'debate'+'is'='debateis'
'debateis' is an anagram of 'DIABETES'.
Can you help me to learn more?
(Other definitions for diabetes that I've seen before include "Disorder causing excessive urination" , "Is debate about disease of bodily sugar and starch?" , "Beadiest sort of bodily disease" , "illness" , "Blood disorder" .)