Ideas about hiding wager becomes a disease (8)
I believe the answer is:
diabetes
'a disease' is the definition.
(diabetes is a kind of gland disease)
'ideas about hiding wager' is the wordplay.
'about' is an anagram indicator.
'hiding' indicates putting letters inside.
'wager' becomes 'bet' (synonyms).
'ideas' is an anagram of 'diaes'.
'diaes' going around 'bet' is 'DIABETES'.
'becomes' acts as a link.
(Other definitions for diabetes that I've seen before include "medical condition" , "Sugar-related disorder" , "Disorder causing excessive urination" , "Insulin-linked disorder" , "Disease of abnormally high blood glucose levels" .)