Newton's overwhelmed by genius somehow succeeding (7)
I believe the answer is:
ensuing
'succeeding' is the definition.
('ensuing' can be similar in meaning to 'succeeding')
'newton's overwhelmed by genius somehow' is the wordplay.
'newton' becomes 'n' ('N' can be a synonym of 'newton').
'overwhelmed by' indicates putting letters inside (I've seen this in other clues).
'somehow' indicates an anagram.
'genius' is an anagram of 'ensuig'.
'n' going inside 'ensuig' is 'ENSUING'.
(Other definitions for ensuing that I've seen before include "This is coming after" , "Immediately following" , "Resulting" , "Happening afterwards" , "Following as a result" .)