A prominence

She has achieved a prominence she hardly deserves.

prominence noun - Definition, pictures, pronunciation and usage notes | Oxford Advanced Learner's Dictionary at OxfordLearnersDictionaries.com
Why have they used "a" before "prominence"?
Prominence is defined as uncountable

Uncountable nouns do not normally have a plural form. But despite being “uncountable”, they can in some circumstances take the determiner “a” to imply that they’re one of a kind (in other words, unique).

Uncountable nouns expressing emotion/mental activity can take the indefinite article + an adjective:

Uncountable nouns can also take the indefinite article + a post-modifier or relative clause:

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