Kind of light, to a great extent (4)
I believe the answer is:
very
This could be a double definition.
'kind of' is the first definition.
(thesaurus)
'light to a great extent' is the second definition.
'very' can be an answer for 'light' (I've seen this before). I am not sure about the 'to a great extent' bit.
Can you help me to learn more?
(Other definitions for very that I've seen before include "Exactly, really" , "Exceedingly" , "Real" , "To a high degree or extent" , "jolly British!" .)