Ran wild in captivity causing great slaughter (7)
I believe the answer is:
carnage
'great slaughter' is the definition.
(I've seen this before)
'ran wild in captivity' is the wordplay.
'wild' indicates anagramming the letters.
'in' indicates putting letters inside.
'captivity' becomes 'cage' (I can't explain this - if you can you should give a lot more credence to this answer).
'ran' with letters rearranged gives 'arn'.
'arn' inserted into 'cage' is 'CARNAGE'.
'causing' acts as a link.
Can you help me to learn more?
(Other definitions for carnage that I've seen before include "Mass slaughter" , "Wholesale killing" , "Bloodbath" , "Widespread killing" , "Bloodshed" .)