Charlie arranged duel outside golf club (6)
I believe the answer is:
cudgel
'club' is the definition.
(I know that cudgel is a type of club)
'charlie arranged duel outside golf' is the wordplay.
'charlie' becomes 'C' (phonetic alphabet: alpha, bravo, charlie etc.).
'arranged' indicates an anagram (letters rearranged).
'outside' is an insertion indicator.
'golf' becomes 'g' (phonetic alphabet: alpha, bravo, charlie etc.).
'duel' with letters rearranged gives 'udel'.
'udel' placed around 'g' is 'udgel'.
'c'+'udgel'='CUDGEL'
(Other definitions for cudgel that I've seen before include "Stout stick used as a weapon" , "Bludgeon" , "Stout stick; hit with this" , "A ruffian's club" , "Heavy stick or club as a weapon" .)