Made an impression when one entered (10)
I believe the answer is:
registered
I believe this is a double definition.
'made an impression' is the first definition.
(I've seen this in another clue)
'one entered' is the second definition.
(thesaurus)
'when' is the link.
(Other definitions for registered that I've seen before include "as post may be" , "As some nurses" , "Officially recorded" , "Enrolled" , "Recorded in writing" .)