Black stuff created by queen's poisoner before arrest (7)
I believe the answer is:
asphalt
'black stuff created by queen's' is the definition.
I can't judge whether this defines the answer.
'poisoner before arrest' is the wordplay.
'poisoner' becomes 'asp' (venomous snake).
'before' is a charade indicator (letters next to each other).
'arrest' becomes 'halt' (synonyms).
'asp'+'halt'='ASPHALT'
Can you help me to learn more?
(Other definitions for asphalt that I've seen before include "What you see on roads" , "Bituminous substance used for roofs and roads" , "Bituminous substance used in building" , "Material for covering roads" , "Roofers use this" .)