A cry for help about top material that's dangerous (8)
I believe the answer is:
asbestos
'material that's dangerous' is the definition.
I can't tell whether this defines the answer.
'a cry for help about top' is the wordplay.
'cry for help' becomes 'sos'.
'about' is an insertion indicator.
'top' becomes 'best' ('best' can be similar in meaning to 'top'**).
'sos' going around 'best' is 'sbestos'.
'a'+'sbestos'='ASBESTOS'
Can you help me to learn more?
(Other definitions for asbestos that I've seen before include "we now know to be dangerous" , "dangerous dust" , "Fire defence" , "risky material" , "Protective fabric" .)