First-class pilot receiving officer promotion and praise (8)

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

An envelope (‘receiving’) of CO (commanding ‘officer’) in ‘a’ plus CLADE ( Emil , WW11 Luftwaffe ‘pilot’). … but see russtoo @2 for a parsing which avoids the name unfamiliar to many (at the expense of using ACE in two adjacent answers).