Almost slight case of indigestion? This affects metabolism (7)
I believe the answer is:
insulin
'affects metabolism' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'almost slight case of indigestion?' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'slight' becomes 'insult' (to slight someone is to insult or disrespect them).
'case of' suggests removing the centre (outsides of).
'indigestion' with its centre taken out is 'in'.
'insult' with its final letter taken away is 'insul'.
'insul'+'in'='INSULIN'
'this' acts as a link.
Can you help me to learn more?
(Other definitions for insulin that I've seen before include "Hormone produced in the pancreas to control body sugar" , "Hormone important to diabetics" , "Secretion, deficiency of which results in diabetes" , "Hormone substance injected by diabetics" , "blood sugar regulated by this" .)