Singer dear to Jean-Paul Sartre (4)

I believe the answer is:

cher

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'singer' is the definition.
(American singer)

I can't explain the rest of the clue.

(Other definitions for cher that I've seen before include "Sonny and - -" , "US singer; dear (Fr.)" , "Moonstruck star" , "Singer; dear (French)" , "1987 Best Actress Oscar winner for "Moonstruck"" .)

I've seen this clue in The Times.

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