Originally called in one engineer (3)
I believe the answer is:
nee
'originally called' is the definition.
(written before eg a maiden name)
'in one engineer' is the wordplay.
'in' indicates a hidden word.
'NEE' is hidden within 'engineer'.
(Other definitions for nee that I've seen before include "Indicates the maiden name of a married woman" , "Adjective used to give woman's maiden name" , "Word used to indicate family name of a married woman" , "Born (to indicate maiden name)" , "It indicates a married woman's single name" .)