Clue: First-class pilot receiving officer promotion and praise (8)
Answer: ACCOLADE
Explanation: Definition: promotion and praise
An envelope ('receiving') of CO (commanding 'officer') in 'a' plus CLADE (, 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).