Because, for example, ultimately it's true (7)
I believe the answer is:
sincere
'true' is the definition.
(synonyms)
'because for example ultimately' is the wordplay.
'because' becomes 'since' (I've seen this before).
'ultimately' says to take the final letters.
The last letters of 'for example' are 're'.
'since'+'re'='SINCERE'
'it's' is the link.
(Other definitions for sincere that I've seen before include "Honest, heartfelt" , "Honest, frank" , "True" , "Free from deceit" , "Not hypocritical" .)