Mike joining excellent club (4)
I believe the answer is:
mace
'club' is the definition.
(mace can mean a club or stick)
'mike joining excellent' is the wordplay.
'mike' becomes 'M' (phonetic alphabet: alpha, bravo, charlie etc.).
'joining' means one lot of letters go next to another.
'excellent' becomes 'ace' (ace can informally mean very good).
'm'+'ace'='MACE'
(Other definitions for mace that I've seen before include "Ceremonial staff or kind of spice" , "One of 9 [CLUBS]" , "something fragrant" , "Came to get ceremonial staff" , "Came to find ceremonial staff" .)