East Germans taking very little time in assimilation (7)
I believe the answer is:
osmosis
'assimilation' is the definition.
(I have seen 'Gradual assimilation' mean 'osmosis' so perhaps 'assimilation' could also mean 'osmosis')
'east germans taking very little time' is the wordplay.
'east germans' becomes 'Ossis' (informal term for citizens of East Germany).
'taking' is an insertion indicator.
'very little time' becomes 'mo' (short period of time).
'ossis' going around 'mo' is 'OSMOSIS'.
'in' acts as a link.
(Other definitions for osmosis that I've seen before include "Becoming absorbed" , "Diffusion through a semi-permeable membrane" , "Absorption (biol.)" , "Absorptive process" , "Passage of bodily fluid through porous partition" .)