Cool drink the setter had without flavour (7)
I believe the answer is:
insipid
'without flavour' is the definition.
'cool drink the setter had' is the wordplay.
'cool' becomes 'in' (I've seen this in other clues).
'drink' becomes 'sip' (I've seen this before**).
'the setter' becomes 'i' (the person that set the crossword).
'had' becomes 'd' (I've seen this in other clues).
'in'+'sip'+'i'+'d'='INSIPID'
(Other definitions for insipid that I've seen before include "Tasteless" , "Lacking 10" , "Dull" , "Boring and lacking liveliness" , "Very weak" .)