Vet's diary displayed hardship (9)
I believe the answer is:
adversity
'hardship' is the definition.
(synonyms)
'vet's diary displayed' is the wordplay.
'displayed' indicates an anagram (letters displayed in another way).
'vets'+'diary'='vetsdiary'
'vetsdiary' anagrammed gives 'ADVERSITY'.
(Other definitions for adversity that I've seen before include "State of misfortune or affliction" , "Misfortune, hardship" , "Hard times or misfortune" , "Circumstances that cause trouble or sorrow" .)