Drink nothing - there’s a teetotaller about! (3)
I believe the answer is:
tot
'drink' is the definition.
(I've seen this before)
'nothing there's a teetotaller about' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'there's a teetotaller' becomes 'tt' (abbreviation).
'about' is an insertion indicator.
'o' going inside 'tt' is 'TOT'.
(Other definitions for tot that I've seen before include "A wee dram" , "quick drink" , "Dram; small child" , "nipper" , "Add up like infant" .)