The process of gradual absorption (7)
I believe the answer is:
osmosis
'the process of gradual absorption' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for osmosis that I've seen before include "Absorption (biol.)" , "Process of gradual absorption" , "Process of unconscious assimilation" , "Process of learning something gradually and without effort" , "Absorptive process" .)