Drug dealer using speed sustains damage (8)
I believe the answer is:
pharmacy
'drug dealer' is the definition.
(I've seen this before)
'speed sustains damage' is the wordplay.
I cannot really see how this works, but
'damage' could be 'harm' (synonyms) and 'harm' is present in the answer.
The remaining letters 'pacy' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'using' acts as a link.
Can you help me to learn more?
(Other definitions for pharmacy that I've seen before include "It supplies drugs" , "where a remedy is sought" , "Dispensary" , "get medicine here?" , "Where chemist works" .)