Teacher with unfinished virtual assistant (3)
I believe the answer is:
sir
'teacher' is the definition.
(a male teacher might be addressed as 'sir')
'unfinished virtual assistant' is the wordplay.
'unfinished' means to remove the last letter.
'virtual assistant' becomes 'siri' (I've seen this in another clue).
'siri' with its final letter taken off is 'SIR'.
'with' acts as a link.
(Other definitions for sir that I've seen before include "Knight's prefix" , "Formal term of address" , "Title for knight or teacher" , "Form of address for a knight" , "Noble title of undesirable kind" .)