One in the red oyster bed is missing? Yes! (6)
I believe the answer is:
debtor
'one in the red' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'oyster bed is missing? yes' is the wordplay.
I cannot quite see how this works, but
an anagram of 'bed' is 'deb' which is located in the answer.
The remaining letters 'tor' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for debtor that I've seen before include "Borrower" , "One owing money" , "Person owing money" , "Opposite of creditor" , "One who owes money" .)