Drain away (5)
I believe the answer is:
leach
'drain away' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for leach that I've seen before include "Percolate - be removed by percolating liquid" , "Drain away through percolating liquid" , "Make liquid percolate through a solid" , "Filtrate" , "Make liquid percolate through soil" .)