Crave terribly object close to jewellery? That's the truth (8)
I believe the answer is:
veracity
'the truth' is the definition.
(thesaurus)
'crave terribly object close to jewellery?' is the wordplay.
'terribly' is an anagram indicator.
'object' becomes 'it' (pronoun for an inanimate object).
'close to' indicates one should take the final letters (the close/ending of).
The last letter of 'jewellery' is 'y'.
'crave' anagrammed gives 'verac'.
'verac'+'it'+'y'='VERACITY'
'that's' is the link.
(Other definitions for veracity that I've seen before include "Habitual truthfulness" , "Exactitude" , "Truthfulness, accuracy" , "Truth" .)