Half-hearted runner's head dropping - Farah starts keener (7)
I believe the answer is:
mourner
'half-hearted runner's head' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for mourner that I've seen before include "Funeral attender" , "Person following the coffin" , "Someone attending a funeral" , "One at a funeral" .)