Storage unit in South African aircraft? (6)
I believe the answer is:
bomber
'aircraft?' is the definition.
(bomber is a kind of aircraft)
'storage unit in south african' is the wordplay.
'storage unit' becomes 'mb' (I can't justify this - if you can you should believe this answer much more).
'in' is an insertion indicator.
'south african' becomes 'boer' (Dutch settler in South Africa).
'mb' placed within 'boer' is 'BOMBER'.
(Other definitions for bomber that I've seen before include "terrorist" , "warplane" , "Military aircraft" , "Aircraft designed to drop high explosives" , "Zip-up garment elasticated at the waist and cuffs" .)