ABC a kid learned initially, awfully relaxed (4-4)
I believe the answer is:
laid-back
'relaxed' is the definition.
('laid-back' can be similar in meaning to 'relaxed')
'abc a kid learned initially awfully' is the subsidiary indication.
'initially' suggests taking the first letters.
'awfully' indicates an anagram.
The first letter of 'learned' is 'l'.
'abc'+'a'+'kid'+'l'='abcakidl'
'abcakidl' is an anagram of 'laidback'.
(Other definitions for laid-back that I've seen before include "Relaxed (colloq.)" , "Ultra-cool!" , "Easygoing and relaxed like cabal kid" , "Unhurried and relaxed" .)