Eventually cheers up, having left close friend (2,4)
I believe the answer is:
in time
'eventually' is the definition.
('in time' can be a synonym of 'eventually')
'cheers up having left close friend' is the wordplay.
'cheers up' becomes 'at' (I've seen this in other clues).
'having left' is a deletion indicator.
'close friend' becomes 'intimate' (I've seen this before).
'intimate' with 'at' taken away is 'IN TIME'.
(Other definitions for in time that I've seen before include "What musicians aim to be" , "not too late" , "What an orchestra should be" , "eventually" , "Early enough" .)