You and me have period of employment (5)
I believe the answer is:
usage
'employment' is the definition.
('usage' can be a synonym of 'employment')
'you and me have period' is the wordplay.
'you and me' becomes 'us'.
'have' is a charade indicator (letters next to each other).
'period' becomes 'age' (I've seen this before).
'us'+'age'='USAGE'
'of' is the link.
(Other definitions for usage that I've seen before include "Habit" , "Acceptable language" , "Customary way in which language is spoken or written" , "Customary practice" , "Common practice" .)