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