Only parts of Biscay? (3)
I believe the answer is:
bay
'only parts' is the definition.
'bay' can be an answer for 'parts' (thesaurus). I'm not certain of the 'only' bit.
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for bay that I've seen before include "laurel maybe" , "Sea inlet" , "Broad curved inlet" , "Reddish-brown horse" , "Botany, Galway or Tampa" .)