Approximately, timewise (5)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
circa
(Other definitions for circa that I've seen before include "Preposition meaning about, usually preceding a date" , "About, say, a date" , "Preceding a date, this means about" , "Approximately (Lat.)" , "(Especially of a date) approximately" .)