First of elite joining crack outfit (5)
I believe the answer is:
equip
'outfit' is the definition.
('equip' can be a synonym of 'outfit')
'first of elite joining crack' is the wordplay.
'first of' says to take the initial letters.
'joining' is a charade indicator (letters next to each other).
'crack' becomes 'quip' ('quip' can be a synonym of 'crack'**).
The first letter of 'elite' is 'e'.
'e'+'quip'='EQUIP'
(Other definitions for equip that I've seen before include "Provide with requirements" , "Provide with kit" , "Furnish with supplies" , "Provide everything that is required'" , "Give what's needed" .)