Explain in detail charm is not worth considering (5,3)
I believe the answer is:
spell out
'explain in detail' is the definition.
(I've seen this in another clue)
'charm is not worth considering' is the wordplay.
'charm' becomes 'spell' (both can mean a bit of magic).
'is not worth considering' becomes 'out' (I've seen this in another clue).
'spell'+'out'='SPELL OUT'
(Other definitions for spell out that I've seen before include "Temporary release from prison" , "Give precise details" , "Explain in detail" , "writing letters?" .)