Bad luck in race -- she and he'd fallen (4,6)
I believe the answer is:
hard cheese
'bad luck' is the definition.
(I've seen this before)
'race she and he'd fallen' is the wordplay.
'and' says to put letters next to each other (I've seen this in other clues).
'fallen' indicates anagramming the letters.
'race'+'she'='raceshe'
'raceshe' put after 'hed' is 'hedraceshe'.
'hedraceshe' with letters rearranged gives 'HARD CHEESE'.
'in' acts as a link.
(Other definitions for hard cheese that I've seen before include "Expression of sympathy" , "Bad luck! (Grate it!)" , "Leicester" , "Che sfortuna!" , "Tough luck (informal)" .)