Decoration badly made by learner (5)
I believe the answer is:
medal
'decoration' is the definition.
('medal' can be a synonym of 'decoration')
'badly made by learner' is the wordplay.
'badly' is an anagram indicator.
'by' says to put letters next to each other.
'learner' becomes 'l'.
'made' is an anagram of 'meda'.
'meda'+'l'='MEDAL'
(Other definitions for medal that I've seen before include "Lamed (anag)" , "Prize; sounds like interfere" , "sort of play" , "Commemorative piece of metal" , "Award for service" .)