Scientist terribly close to GI (9)
I believe the answer is:
ecologist
'scientist' is the definition.
(I know that ecologist is a type of scientist)
'terribly close to gi' is the wordplay.
'terribly' is an anagram indicator.
'close'+'to'+'gi'='closetogi'
'closetogi' is an anagram of 'ECOLOGIST'.
(Other definitions for ecologist that I've seen before include "Studier of organisms and the environment" , "Student of living things and their environment" , "Company's possessions" , "See scientist" , "Environmentalist" .)