Exudation (7)
I believe the answer is:
seepage
'exudation' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for seepage that I've seen before include "Slowly leaking flow" , "Oozing liquid" , "liquid having soaked through" , "Slow fluid loss" , "Slow leakage" .)