Male fowl left on top of eggs one shelled (6)
I believe the answer is:
cockle
'eggs one shelled' is the definition.
I can't tell whether this defines the answer.
'male fowl left on top' is the wordplay.
'male fowl' becomes 'cock' (cock is a kind of fowl. I am not sure about the 'male' bit.).
'left' becomes 'l' (common abbreviation).
'on' becomes 're' ('on' can be mean 'with reference to').
'top' means to remove the first letter.
're' with its first letter removed is 'e'.
'cock'+'l'+'e'='COCKLE'
'of' is the link.
Can you help me to learn more?
(Other definitions for cockle that I've seen before include "Common edible bivalve" , "Seafood item" , "Mollusc - cornfield weed" , "Edible bivalve mollusc" , "Shellfish" .)