Boffins (10)
'boffins' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for scientists that I've seen before include "Eg, physicists, biologists" , "Insects sit (anag.)" , "Boffins" , "They study" .)
(Other definitions for nerds that I've seen before include "Boringly studious types" , "People considered boring because of obsessive hobbies or narrow solitary interests" , "They can be boringly studious, perhaps lacking social skills" , "Boringly studious people" , "Geeks" .)