Just had a thought that she might be on a UK census before she went to SA.
I found this one (of course if Magee is her married name then it's nothing to do with her)
1881 census
Daniel Curr Magee 45 coach builder/maker Ireland, Antrim
Mary Magee 40 Ireland, Antrim
Catharine Magee 20 , Ireland , Antrim
Joseph J. Magee 16 , Painter’s Apprentice ,Salop, Ludlow
Mary J. Magee 14 , Scholar,Lancs ,Manchester
Clara Margaret C. Magee 7 ,Scholar, Ireland, Antrim
Maud A. Magee 4 Ireland, Antrim
Horatio N. Magee 1, Lancashire, Manchester
They were living at 34, Bond Street,Broughton Salford.
Class: RG11; Piece: 3956; Folio: 70; Page: 6; GSU roll: 1341945
Ancestry.com and The Church of Jesus Christ of Latter-day Saints. 1881 England Census [database on-line]. Provo, UT, USA: Ancestry.com Operations Inc, 2004
I can't find her on the 1891 census but there a ships passenger list that makes this Clara a possibility (note the initial and age of sister)
Miss C Magee Female 21 1874 20 Apr 1895 Southampton, England Cape Goth
Miss M Magee Female 16 1879 20 Apr 1895 Southampton, England Cape Goth
Ancestry.com. UK, Outward Passenger Lists, 1890-1960 [database on-line]. Provo, UT, USA: Ancestry.com Operations, Inc., 2012