Am icing a concoction; must be a wonder-worker! (8)
I believe the answer is:
magician
'a wonder-worker' is the definition.
I can't judge whether this definition defines the answer.
'am icing a concoction' is the wordplay.
'am' becomes 'MA' (synonyms).
'concoction' indicates an anagram.
'icing'+'a'='icinga'
'icinga' with letters rearranged gives 'gician'.
'ma'+'gician'='MAGICIAN'
'must be' acts as a link.
Can you help me to learn more?
(Other definitions for magician that I've seen before include "Conjurer, illusionist" , "Conjuror, illusionist" , "Person with a wand or rabbit in his hat?" , "Conjuror, wizard" , "Stage conjurer or maker of legerdemain" .)