Very; in addition (3)
I believe the answer is:
too
This clue is a double definition.
'very' is the first definition.
(I've seen this before)
'in addition' is the second definition.
(I've seen this before)
(Other definitions for too that I've seen before include "On top - also" , "Moreover, in addition" , "What a pity!" , "To a greater than desirable extent" , "Furthermore" .)