Excited geologist removes oil covering rich and large nutritional source! (7-3)
I believe the answer is:
ostrich-egg
'large nutritional source' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'excited geologist removes oil covering rich' is the wordplay.
'excited' indicates an anagram.
'removes' is a deletion indicator.
'covering' indicates putting letters inside.
'geologist' with 'oil' removed is 'geogst'.
'geogst' with letters rearranged gives 'ostegg'.
'ostegg' placed around 'rich' is 'OSTRICH-EGG'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for ostrich-egg that I've seen before include "Large thing laid" , "It's laid by largest bird" .)