Weapon European concealed in fight (5)
I believe the answer is:
spear
'weapon' is the definition.
(I know that spear is a type of weapon)
'european concealed in fight' is the wordplay.
'european' becomes 'E' (abbreviation e.g. EU).
'concealed in' means one lot of letters goes inside another.
'fight' becomes 'spar' (sparring is a kind of fighting).
'e' put into 'spar' is 'SPEAR'.
(Other definitions for spear that I've seen before include "Stabbing, throwing, weapon" , "stick" , "Portion of asparagus" , "Weapon; asparagus stem" , "Impale" .)