I think Jens' translation is unnatural and slightly flawed, and I am basing mine off of Kohsuke Kawaguchi's correct answer, but making the English more natural.
Well, as for me, it's really just because my aunt referred me that I'm working here.
You know, the reason I'm working here is just because my aunt referred me.
As for me, just because of aunt's referral, is reason I'm working here.
for sure (emphasize preceding word)
conclusion from reasoning, judgement or calculation based on something read or heard; reason; cause; meaning; circumstances; situation;
(I translated it as "because")
noun / noun or participle with aux. verb する → conjugation:
work (esp. part time or casual) —Abbreviation. From German 'Arbeit'. → アルバイト
noun / noun or participle with aux. verb する → conjugation / noun with genitive case particle の: