To arrange the relay is hard (8)
I believe the answer is:
leathery
'is hard' is the definition.
(thesaurus)
'to arrange the relay' is the wordplay.
'to arrange' indicates anagramming the letters.
'the'+'relay'='therelay'
'therelay' with letters rearranged gives 'LEATHERY'.
(Other definitions for leathery that I've seen before include "Tough-textured" , "as old balls?" , "like old boots?" , "Like tough skin" , "(Of skin) having a tough and hard texture" .)