Craft in river very gently rising by Zaire's borders (8)
I believe the answer is:
zeppelin
'craft' is the definition.
(I have seen 'Inflatable craft' mean 'zeppelin' so perhaps 'craft' could also mean 'zeppelin')
'river very gently rising by zaire's borders' is the wordplay.
'river' becomes 'nile' (Nile is an example).
'very gently' becomes 'pp' (musical abbreviation for pianissimo, 'very softly').
'rising' says the letters should be written backwards (going up in a down clue).
'by' says to put letters next to each other.
'borders' suggests removing the centre (only the edge or border letters remain).
'zaire' with its centre removed is 'ze'.
'nile'+'pp'='nilepp'
'nilepp' back-to-front is 'ppelin'.
'ppelin' after 'ze' is 'ZEPPELIN'.
'in' acts as a link.
(Other definitions for zeppelin that I've seen before include "Early German airship" , "German invention" , "Led follower" , "Old airship" , "German inventor of dirigible airship" .)