She'll back saintly Irishman up (5)

I believe the answer is:

nadia

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But I can't explain it at all! Could you help me understand?

(Other definitions for nadia that I've seen before include "Russian woman" , "___ Comaneci, Romanian-born American gymnast" , "Miss" , "(Originally Russian) female name (reverse of Irish male name)" , "Name of girl" .)

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