Very eager to start next page after turning (4,2)
I believe the answer is:
ever so
'very' is the definition.
(I've seen this before)
'eager to start next page after turning' is the wordplay.
'to start' indicates taking the first letters.
'next page after turning' becomes 'verso' (verso is the back of a sheet of paper).
The initial letter of 'eager' is 'e'.
'e'+'verso'='EVER SO'
(Other definitions for ever so that I've seen before include "really" , "Jolly" , "Intensifier" , "Greatly" , "To a very great extent" .)