Lacking flavour in the small drink I had (7)
I believe the answer is:
insipid
'lacking flavour' is the definition.
(I've seen this before)
'in the small drink i had' is the wordplay.
'the small drink' becomes 'sip' (I've seen this in another clue).
'i had' becomes 'I'd' (contraction).
'in'+'sip'+'id'='INSIPID'
(Other definitions for insipid that I've seen before include "Boring and lacking liveliness" , "without taste" , "devoid of flavour" , "Colourless" , "Lacking taste or flavour" .)