Single name within department for one under oath (8)
I believe the answer is:
deponent
'one under oath' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'single name within department' is the wordplay.
'single' becomes 'one' (a single thing - only one).
'name' becomes 'n' (common abbreviation e.g. on forms).
'within' is an insertion indicator.
'department' becomes 'dept'.
'one'+'n'='onen'
'onen' inserted within 'dept' is 'DEPONENT'.
'for' is the link.
Can you help me to learn more?
(Other definitions for deponent that I've seen before include "One making a statement under oath" , "Person giving evidence under oath" .)