Duck keeping tail of the little one dry (8)
I believe the answer is:
teetotal
'dry' is the definition.
(I know that dry can be written as teetotal)
'duck keeping tail of the little one' is the wordplay.
'duck' becomes 'teal' (teal is a type of duck).
'keeping' indicates putting letters inside (some letters kept inside).
'tail of' says to take the final letters.
'little one' becomes 'tot' (I've seen this in another clue).
The final letter of 'the' is 'e'.
'e'+'tot'='etot'
'teal' enclosing 'etot' is 'TEETOTAL'.
(Other definitions for teetotal that I've seen before include "Completely dry" , "refusing to drink" , "Non-drinking" , "Abjuring alcohol" , "Avoiding alcohol" .)