Disastrous little bit of toxic smoke rising (6)
I believe the answer is:
tragic
'disastrous' is the definition.
(I've seen this before)
'little bit of toxic smoke rising' is the wordplay.
I cannot quite understand how this works, but
'bit' could be 'rag' (I have seen 'Bit of cloth ' mean 'rag' so perhaps 'bit' could also mean 'rag') and 'rag' is present in the answer.
The remaining letters 'tic' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for tragic that I've seen before include "Disastrous, desperately sad" , "'Very, very sad (6)'" , "Pathetic" , "Deeply distressing" , "Shocking" .)