Blood cells' origin is one male interred in burial mound (4,6)
I believe the answer is:
bone marrow
'blood cells' origin is one male' is the definition.
I can't tell whether this definition defines the answer.
'interred in burial mound' is the wordplay.
'interred' becomes 'onem' (I can't explain this - if you can you should believe this answer much more).
'in' indicates putting letters inside.
'burial mound' becomes 'barrow' (ancient burial mound).
'onem' put within 'barrow' is 'BONE MARROW'.
Can you help me to learn more?
(Other definitions for bone marrow that I've seen before include "Vital part of skeleton" , "Fatty network of connective tissue" , "Where blood cells are manufactured" , "Soft tissue" , "transplant tissue" .)