Each of the given clues has had one or two transformations applied to each word in the clue. Applying these same transformations to the answer to that clue yields the name of a nut.
VENOMOUS SERPENT KILLING MEERKAT RELATIVE (Replace last three letters with previous three) = MONGOOSE → MONGONGO
GRAIN ALSO KNOWN AS MAIZE (Add A before each word) = CORN → ACORN
ARBOREAL MARSUPIAL KNOWN FOR EATING EUCALYPTUS (Remove third letter) = KOALA → KOLA
MUSICAL PARTNER OF SULLIVAN (First letters shifted backwards in the alphabet by one) = GILBERT → FILBERT
ETHEREAL BLOOD OF THE GODS (Replace H with K; add H and Y around each word) = ICHOR → HICKORY
LOVABLE FURRY BLUE MUPPET (Add MAN to beginning; remove final letter) = GROVER → MANGROVE
CARTER VICE PRESIDENT (Remove final letter; move previous two letters to front of word) = MONDALE → ALMOND
BREAKFAST FOOD OR TORUS (Shift first letters backwards in the alphabet by one; duplicate first two letters) DONUT → COCONUT
SANDY PLACE BY SOME SEAS (Replace each word with a homophone) = BEACH → BEECH
COINS AND BILLS (Add EW to the end of the word) = CASH → CASHEW
BLACK AND WHITE STRIPED AFRICAN HERBIVORE (Move first two letters to the end of the word; replace E with IL) = ZEBRA → BRAZIL
The next step is the use the numbers given to index into the names of the nuts. (1 is the first letter; 2 the second, etc.) This spells out the solution GOOFY GOOBER.