Precious spirit, litre gone inside (7)
I believe the answer is:
darling
'precious' is the definition.
(thesaurus)
'spirit litre gone inside' is the wordplay.
I cannot quite understand how this works, but
'litre' could be 'l' (synonyms) and 'l' is found in the answer.
'spirit' could be 'daring' (daring is a kind of spirit) and 'daring' is found in the leftover letters.
No letters remain.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for darling that I've seen before include "Beloved" , "Australian river and loved one" , "Pet" , "lover" , "Adorable - honeybun" .)