Doing well, a learner relaxed (8)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
informal
'relaxed' is the definition.
(thesaurus)
'doing well a learner' is the wordplay.
'doing well' becomes 'inform'.
'learner' becomes 'l'.
'inform'+'a'+'l'='INFORMAL'
(Other definitions for informal that I've seen before include "Casual or unofficial" , "Casual and unceremonious" , "Cosy -- loose" , "Casual, free and easy" , "If normal, be casual and without ceremony" .)