Significant time to worry about losing face (3)
I believe the answer is:
era
'significant time' is the definition.
(I've seen this before)
'worry about losing face' is the wordplay.
'worry' becomes 'er' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'about' becomes 'ca' (circa).
'losing face' means to remove the first letter.
'ca' with its first letter taken away is 'a'.
'er'+'a'='ERA'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for era that I've seen before include "Long period of history" , "8" , "Geological age" , "Age of importance" , "Long historic period" .)