Mean to declare before time (7)
I believe the answer is:
average
'mean' is the definition.
('average' can be a synonym of 'mean')
'declare before time' is the wordplay.
'declare' becomes 'aver' (averring is a kind of declaring**).
'before' is a charade indicator (letters next to each other).
'time' becomes 'age' (age is a kind of time).
'aver'+'age'='AVERAGE'
'to' acts as a link.
(Other definitions for average that I've seen before include "Mean - typical" , "Arithmetic mean" , "Run of the mill" , "Normal in arithmetic way" , "Mean - medium" .)