Hindu "sir" (4)
I believe the answer is:
babu
'hindu sir' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for babu that I've seen before include "may be superficially learned" , "title in India" , "Title for Indian" , "Indian form of address for a man" , "Respectful title for man" .)