Weapon in Franco’s hand (4)
I believe the answer is:
cosh
'weapon' is the definition.
(I have seen 'Blunt weapon' mean 'cosh' so perhaps 'weapon' could also mean 'cosh')
'in franco's hand' is the wordplay.
'in' indicates the answer is hidden within the clue.
'COSH' can be found hidden inside 'francos hand'.
(Other definitions for cosh that I've seen before include "Sap" , "Heavy stick-like weapon" , "Blackjack" , "Blunt weapon, often of hard rubber" , "Truncheon, bludgeon" .)