I've looked further into Clara's parents -- her mother is identified as "Hendrikje Levie" on http://dutchjewry.org/genealogie/gezin/hum_ashken/F18462/I38774 . There are two Hendrikje Levie's in Akevoth and neither is a suitable parent -- one (http://dutchjewry.org/genealogie/gezin/hum_ashken/F4906/I7159 ) was only 14yo at Clara's birth -- that's pre-puberty back then, isn't it? The other was 41yo at Clara's birth, Hendrikje Anna Levie (http://dutchjewry.org/genealogie/gezin/hum_ashken/F4534/I6546 ), but she looks to have been in a normal marriage and even had a stillborn child in that year so couldn't have been Clara's mother. However, I do think she is the one that Akevoth identifies -- we're in the realm of speculation here, but it looks to me that she raised her sister's child from infancy.
http://dutchjewry.org/genealogie/gezin/hum_ashken/F4535/I16719 shows that Hendrikje had a sister Vrouwtje, and she is described more fully on http://dutchjewry.org/genealogie/gezin/hum_ashken/F9823/I16717 . She was married in 1754 but from 1754-1760 there's no record of any offspring, stillborn or anything. They were apparently barren. The page describes a child, Judic Asser, born in 1762 but a close reading reveals that the mother was a different woman, a "Sientje". Evidently (unless the record is wrong) they had a falling out, maybe blaming each other for the barrenness. Vrouwtje died in 1763, mysteriously, and her husband remarried within 4 months. Was she killed because she refused to give a divorce? (as I said, in the realm of speculation here)
If Clara was in fact a daughter of Vrouwtje (with an unknown "Victor"), she would be just 1 year old when her mother died. It makes sense that Hendrikje would raise her dead sister's child in her own house, and that by the time of Clara's marriage she would be seen as the daughter of Hendrikje, or as good as.
As for the father, "Victor", I can find no good candidate in Akevoth. Maybe it was a seaman? The mists of time are thick. But as Hendrikje Levie's sister died in 1763, 2 years after Clara's birth, I think it a fair chance that Hendrikje raised her sister's infant child. However, no such infant is mentioned in Akevoth, so this is a hypothetical scenario only -- but the best I can do.
Reading more closely from http://dutchjewry.org/genealogie/gezin/hum_ashken/F9823/I16717 , I see Vrouwtje's husband got engaged to his 2nd wife in the IMMEDIATE NEXT MONTH after Vrouwtje's death. Is this a "cold case" or what?
Clara called herself "Klaartje", that style evidently being a family tradition from her mother(s) Vrouwtje and Hendrikje. She passed it onto her daughters who were called Heintje, Betje and Meitje. Having had time for reflection, I'm satisfied that Vrouwtje is correctly identified as Clara's biological mother as all known facts are consistent with the reasonable scenario that Hendrikje (Vrouwtje's older sister) raised Clara from babyhood after Vrouwtje's untimely death.