Easy to read stage direction involving one boy leaving initially (7)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

[LEG(a stage/section of a journey or process, say, a competition) + E(abbrev. for “east”, direction towards where the sun rises on the horizon)] containing ( involving ) [ I(Roman numeral for “one”) + 1st letters, respectively, of ( … initially ) “ boy leaving ”].