Clue: Arab members of militia ignoring old instructor, initially (6)
Answer: YEMENI
Explanation: Definition: Arab
 "yeomen"(historically, members of the volunteer militia force raised from the civilian yeomanry/men who held small landed estates) **minus**(ignoring) "o"(abbrev. for "old") + **1st letter of**(…, initially) "instructor".
Defn: …, specifically from Yemen.