Girl that is missing somewhere in South Africa (5)
I believe the answer is:
natal
'in south africa' is the definition.
(I've seen this before)
'girl that is missing somewhere' is the wordplay.
'girl' becomes 'nat'.
'that is missing somewhere' becomes 'al' (I can't justify this - if you can you should give a lot more credence to this answer).
'nat'+'al'='NATAL'
Can you help me to learn more?
(Other definitions for natal that I've seen before include "Native" , "description of delivery" , "Like a seat" , "Relating to the time of one's birth" , "Province of South Africa" .)