I go deeper leaving nothing out in family tree (8)
I believe the answer is:
pedigree
'family tree' is the definition.
(pedigree is a kind of family tree)
'i go deeper leaving nothing out' is the wordplay.
'leaving' is a deletion indicator.
'nothing' becomes 'o' (looks like zero - 0).
'out' is an anagram indicator (out can mean wrong or inaccurate).
'i'+'go'+'deeper'='igodeeper'
'igodeeper' with 'o' removed is 'igdeeper'.
'igdeeper' with letters rearranged gives 'PEDIGREE'.
'in' acts as a link.
(Other definitions for pedigree that I've seen before include "(Distinguished) lineage" , "Record of descent" , "Pure lineage" , "Lineage, ancestry" , "High-class" .)