Brobdingnag residents (6)
I believe the answer is:
giants
'brobdingnag residents' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for giants that I've seen before include "Behbmoths, titans" , "eg The inhabitants of Brobdingnag" , "they're big" , "Large mythical beings" , "men of great power?" .)