Gamble moved aside about disease (8)
I believe the answer is:
diabetes
'disease' is the definition.
(diabetes is a kind of gland disease)
'gamble moved aside about' is the wordplay.
'gamble' becomes 'bet' (betting is a kind of gambling).
'moved' is an anagram indicator.
'about' is an insertion indicator.
'aside' anagrammed gives 'diaes'.
'bet' going within 'diaes' is 'DIABETES'.
(Other definitions for diabetes that I've seen before include "Beadiest sort of bodily disease" , "Insulin-related disorder" , "Disease of abnormally high blood glucose levels" , "Disorder linked to insulin" , "Effect of lack of insulin" .)