Carry a torch for hauling up those inside active volcano (4)

I believe the answer is:

love

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'carry a torch' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps they are linked in a way I don't understand?

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

Can you help me to learn more?

(Other definitions for love that I've seen before include "See 22" , "Fondness" , "Passionate desire" , "See 4" , "Feel great affection for" .)

I've seen this clue in The Irish Times.

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