Keep in favour of time (4)
I believe the answer is:
fort
'keep' is the definition.
(I've seen this before)
'in favour of time' is the wordplay.
'in favour of' becomes 'for' (being for a particular cause).
'time' becomes 't' (abbreviation).
'for'+'t'='FORT'
(Other definitions for fort that I've seen before include "William in Scotland" , "Citadel" , "Defensive building" , "US gold reserves are at - Knox" , "Garrison" .)