Before demise, finally try to make different close friend (5,3)
I believe the answer is:
alter ego
'close friend' is the definition.
'before demise finally try to make different' is the wordplay.
'before' is a charade indicator (letters next to each other).
'finally' indicates one should take the final letters.
'try' becomes 'go' (go is a kind of try).
'to make different' becomes 'alter' (I've seen this before).
The last letter of 'demise' is 'e'.
'e'+'go'='ego'
'ego' put after 'alter' is 'ALTER EGO'.
(Other definitions for alter ego that I've seen before include "Other half" , "Go, relate to other self" , "Hidden self or very close friend" , "One's secondary personality" , "Similar character" .)