Damage muscle say in race (4)
I believe the answer is:
tear
This clue might be a double definition.
'damage muscle say' is the first definition.
'tear' can be an answer for 'damage' (thesaurus). I am not sure about the 'muscle say' bit.
'race' is the second definition.
(I know that tear is a more specific form of race)
'in' is the link.
Can you help me to learn more?
(Other definitions for tear that I've seen before include "Droplet; rip" , "Secretion of the lachrymal glands" , "Lachrymal fluid" , "Optical sign of sorrow" , "A rip and a sign of sadness" .)