Roy Orbison's book promoted without article in African language (4)

I believe the answer is:

igbo

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'language' is the definition.
(I have seen 'Nigerian language ' mean 'igbo' so perhaps 'language' could also mean 'igbo')

I cannot understand how the rest of the clue works.

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(Other definitions for igbo that I've seen before include "people abroad" , "language in Nigeria" , "Nigerian language" .)

I've seen this clue in The Independent.

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