It’s used during negotiations in lounge before securing drug at a joint (10,4)
I believe the answer is:
bargaining chip
'it's used during negotiations' is the definition.
I can't judge whether this definition defines the answer.
'in lounge before securing drug at a joint' is the wordplay.
I cannot really see how this works, but
'in' could be 'hip' (both can mean fashionable) and 'hip' is found within the answer.
'lounge' could be 'bar' and 'bar' is located in the answer.
'securing' could be 'gaining' (gaining is a kind of securing) and 'gaining' is found within the answer.
'drug' could be 'c' (C is an example) and 'c' is found within the answer.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for bargaining chip that I've seen before include "Something to be used in negotiations" , "asset in trading" , "A means of leverage" .)