Perhaps one's taken in drink (6)
I believe the answer is:
waiter
'perhaps one's taken in drink' is the definition.
I can't judge whether this definition defines the answer.
'one's taken in drink' is the wordplay.
'one's taken' becomes 'i' (I can't explain this - if you can you should believe this answer much more).
'in' is an insertion indicator.
'drink' becomes 'water' (I've seen this in another clue).
'i' put inside 'water' is 'WAITER'.
Can you help me to learn more?
(Other definitions for waiter that I've seen before include "Servant in bar" , "Server in restaurant" , "Restaurant staff member" , "Herr Ober (Ger.)" , "Attendant" .)