Absence of d-drink? Or a small amount (6)
I believe the answer is:
Here is my best explanation:
'a small amount' is the definition.
(a small amount of alcohol)
'absence of d-drink?' is the wordplay.
'absence of' becomes 'no'.
'd-drink?' becomes 'ggin' ('gin' said with a stammer like 'drink?' was; gin is a kind of drink).
'or' acts as a link.