Mostly lacking knowledge about current matter as a whole (8)
I believe the answer is:
universe
'mostly lacking knowledge' is the definition.
'universe' can be an answer for 'knowledge' (universe is a kind of knowledge). I'm unsure of the 'mostly lacking' bit.
'current matter as a whole' is the wordplay.
I cannot quite see how this works, but
'current' could be 'i' (symbol for electric current) and 'i' is present in the answer.
'matter' could be 'se' (Se is an example) and 'se' is located in the answer.
This explanation may well be incorrect...
'about' is the link.
Can you help me to learn more?
(Other definitions for universe that I've seen before include "Everything that exists anywhere" , "The whole world" , "Edible crustacean" , "The totality of matter, energy and space" , "sphere of activity" .)