One without real authority led the way at sea (10)
I believe the answer is:
figurehead
'sea' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'one without real authority led the way' is the wordplay.
I cannot quite see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is found within the answer.
'real' could be 'e' (e is a kind of real) and 'e' is found in the answer.
'way' could be 'e' (Compass direction - East) and 'e' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'at' is the link.
Can you help me to learn more?
(Other definitions for figurehead that I've seen before include "bust from the navy" , "Person without real power" , "may be bust" , "Front man" , "Nominal leader; carved bust at prow of ship" .)