Half cranky about cavity that might cause disease (7)
I believe the answer is:
cholera
'disease' is the definition.
(cholera is a kind of health problem)
'half cranky about cavity' is the wordplay.
'half' indicates taking half.
'about' is an insertion indicator.
'cavity' becomes 'hole' (hole is a kind of cavity).
'cranky' halved is 'cra'.
'cra' going around 'hole' is 'CHOLERA'.
'that might cause' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for cholera that I've seen before include "Disease contracted from infected water" , "Deadly, infectious disease" , "Disease caught from contaminated water" , "Acute intestinal infection from contaminated water or food" , "Intestinal infection caused by contaminated water or food" .)