The shutter is heavier (6)

I believe the answer is:

closer

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'heavier' is the definition.
Both the definition and answer are comparative adjectives. Perhaps they are linked in a way I don't understand?

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

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(Other definitions for closer that I've seen before include "not so remote" , "Stuffier" , "More airless; nearer" , "Nearer or more intimate" , "Less distant" .)

I've seen this clue in the Evening Standard.

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