Block article about Republican Party in South Africa (7)
I believe the answer is:
tranche
'block' is the definition.
(I've seen this before)
'article about republican party in south africa' is the wordplay.
'article' becomes 'the' (the definite article).
'about' means one lot of letters goes inside another.
'republican' becomes 'R' (abbreviation).
'party in south africa' becomes 'anc' (African National Congress, South African party).
'r'+'anc'='ranc'
'the' placed around 'ranc' is 'TRANCHE'.
(Other definitions for tranche that I've seen before include "issue of shares, perhaps" , "Slice (of income)" , "Portion of something, money perhaps" , "Block of shares, say" , "Portion, slice" .)