Though false, they possibly have value in Isleworth (4)

I believe the answer is:

lies

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'though false they' is the definition.
The definition suggests a plural noun which matches the answer.

I can't explain the remainder of the clue.

(Other definitions for lies that I've seen before include "Perversions of the truth" , "Untruths" , "Wallows" , "False statements" , "pork pies" .)

I've seen this clue in the Evening Standard.

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