Seeking out a key for what's melodically memorable (8)
I believe the answer is:
haunting
'memorable' is the definition.
(haunting can mean evocative or memorable)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for haunting that I've seen before include "Poignant, evocative" , "Ghost visitation on ninth Aug" , "Willing to take chances" , "Visiting as a ghost" , "Frequenting a place, as a ghost might" .)