Grow pale when fan enters at the front of the building (6)

I believe the answer is:

facade

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'front of the building' is the definition.
'facade' can be an answer for 'front' (facade is a kind of front). I'm not certain of the 'of the building' bit.

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for facade that I've seen before include "Front - mask" , "Front; work by Walton" , "Show" , "Surface of building (6)" , "Deceptive front" .)

I've seen this clue in The Irish Times.

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