Author audibly expressed regret for destruction of life-support system (7)
I believe the answer is:
ecocide
'destruction of life-support system' is the definition.
I can't tell whether this definition defines the answer.
'author audibly expressed regret' is the wordplay.
'author' becomes 'eco' (I've seen this before).
'audibly expressed regret' becomes 'cide' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'eco'+'cide'='ECOCIDE'
'for' is the link.
Can you help me to learn more?
(Other definitions for ecocide that I've seen before include "Environmental ruin" , "Destruction of the natural environment" , "Deliberate destruction of the environment" .)