He went inventively ahead as a physicist (6)
I believe the answer is:
newton
'a physicist' is the definition.
(Sir Isaac Newton)
'he went inventively ahead' is the wordplay.
I cannot quite see how this works, but
an anagram of 'went' is 'newt' which is within the answer.
'ahead' could be 'on' (synonyms) and 'on' is present in the answer.
No letters remain.
This explanation may well be incorrect...
'as' acts as a link.
Can you help me to learn more?
(Other definitions for newton that I've seen before include "Great English scientist who discovered gravity" , "English mathematician and physicist, d. 1727" , "Scientist - unit of force" , "Famous mathematician" , "Sir Isaac . . . . . ., great English mathematician" .)