Trial arranged within following year is failing (7)
I believe the answer is:
frailty
'is failing' is the definition.
(thesaurus)
'trial arranged within following year' is the wordplay.
'arranged' is an anagram indicator.
'within' means one lot of letters goes inside another.
'following' becomes 'f' (used when citing page numbers etc**).
'year' becomes 'y'.
'trial' with letters rearranged gives 'railt'.
'f'+'y'='fy'
'railt' going into 'fy' is 'FRAILTY'.
(Other definitions for frailty that I've seen before include "Debility, feebleness" , "Its name is woman (Hamlet)" , "Weakness" , "Shakespeare: '. . . . . . ., thy name is woman!'" , "Weak state, moral or physical" .)