Turn up in tie at the same time (8)
I believe the answer is:
together
'at the same time' is the definition.
('together' can be a synonym of 'at the same time')
'turn up in tie' is the wordplay.
'turn' becomes 'tog' (togging is a kind of turning).
'up in tie' becomes 'ether' (I am not sure about this - if you are sure you should believe this answer much more).
'tog'+'ether'='TOGETHER'
Can you help me to learn more?
(Other definitions for together that I've seen before include "without a break?" , "Married" , "in league" , "United; in agreement" , "United; touching" .)