Extracted natural moisture bordering river (4)
I believe the answer is:
drew
'extracted' is the definition.
(I've seen this in another clue)
'natural moisture bordering river' is the wordplay.
'natural moisture' becomes 'dew' (I've seen this in another clue).
'bordering' means one lot of letters goes inside another.
'river' becomes 'r' (abbreviation for river).
'dew' going around 'r' is 'DREW'.
(Other definitions for drew that I've seen before include "Sketched or tied in a game" , "was attractive" , "--- Barrymore, actress; sketched" , "took in" , "Dragged, sketched" .)