Pale old penny that's used by a magician (4)
I believe the answer is:
wand
'a magician' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'pale old penny that's used by' is the wordplay.
'pale' becomes 'wan' (wan can mean pale or grey).
'old penny' becomes 'd' (pre-decimal abbreviation for penny).
'that's used by' says to put letters next to each other.
'wan'+'d'='WAND'
Can you help me to learn more?
(Other definitions for wand that I've seen before include "spelling aid" , "Dawn (anag.)" , "Wizard's rod" , "Magician's accessory" , "Magic rod?" .)