The boss sent out learners (8)
I believe the answer is:
students
'learners' is the definition.
(student is a kind of learner)
'the boss sent out' is the wordplay.
'the boss' becomes 'stud' (both can mean a metal decoration).
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'sent' is an anagram of 'ents'.
'stud'+'ents'='STUDENTS'
(Other definitions for students that I've seen before include "School or university attendees" , "Sent dust to those who learn" , "Learners as at school" , "Pupils or apprentices" , "Eg, undergraduates" .)