Gradual assimilation of ideas (7)
I believe the answer is:
osmosis
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">gradual assimilation of ideas</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for osmosis that I've seen before include "Diffusion of liquid through porous barrier" , "Something like dialysis" , "Absorptive process" , "gradual diffusion" , "Diffusion of liquid through porous membrane" .)