Ancient civilization originally capturing unknown tribespeople for evisceration (5)
I believe the answer is:
aztec
'evisceration' is the definition.
Both the definition and answer are singular nouns.
Perhaps they are linked in a way I don't understand?
'ancient civilization originally capturing unknown tribespeople' is the wordplay.
'originally' suggests taking the first letters.
'capturing' indicates putting letters inside.
'unknown' becomes 'z' (algebra).
'tribespeople' becomes 'te' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
The initial letters of 'ancient civilization' is 'ac'.
'z'+'te'='zte'
'ac' placed around 'zte' is 'AZTEC'.
'for' is the link.
Can you help me to learn more?
(Other definitions for aztec that I've seen before include "Central American language" , "Former Mexican - Indian race" , "Old Mexican empire" , "Old empire of Mexico" , "Conquered Mexican" .)