Note about that fellow you employed in the past (4)
I believe the answer is:
thee
'you employed in the past' is the definition.
(historic version of 'you')
'note about that fellow' is the wordplay.
'note' becomes 'te' (**).
'about' is an insertion indicator.
'that fellow' becomes 'he' (I've seen this in other clues).
'te' placed around 'he' is 'THEE'.
(Other definitions for thee that I've seen before include "Poetically you" , "you many years ago" , "Quaker 'you'" , "You (arch.)" , "You in the olden days" .)