An indication of interest in astrology (4)

I believe the answer is:

sign

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'an indication' is the definition.
(I know that indication can be written as sign)

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for sign that I've seen before include "house" , "Signal, gesture" , "Public notice; portent" , "part of the zodiac" , "Indication; symbol" .)

I've seen this clue in the Evening Standard.

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