Non-drinker in fancy tutu having expression of disapproval (3-3)
I believe the answer is:
tut-tut
'expression of disapproval' is the definition.
(I've seen this before)
'non-drinker in fancy tutu' is the wordplay.
'non drinker' becomes 'tt' (abbreviation for teetotaller).
'in' is an insertion indicator.
'fancy' indicates anagramming the letters.
'tutu' with letters rearranged gives 'tuut'.
'tt' placed within 'tuut' is 'TUT-TUT'.
'having' acts as a link.
(Other definitions for tut-tut that I've seen before include "Sounds of disapproval" , "Repetitive exclamation of disapproval or annoyance" , "That's bad" , "Expression of disapproval, contempt" , "Repetitive exclamation of annoyance or rebuke" .)