Provide European with gag (5)
I believe the answer is:
equip
'provide' is the definition.
(equipping is a kind of providing)
'european with gag' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'with' is a charade indicator (letters next to each other).
'gag' becomes 'quip' ('quip' can be a synonym of 'gag').
'e'+'quip'='EQUIP'
(Other definitions for equip that I've seen before include "Provide everything that is required'" , "Furnish with supplies" , "Accoutre" , "Provide what's needed" , "Give everything needed" .)