Wrath more dangerous than invertebrate? (9)

I believe the answer is:

earthworm

I'm a little stuck... Click here to teach me more about this clue!

'invertebrate?' is the definition.
(earthworm is a kind of invertebrate)

'wrath more dangerous' is the wordplay.
'wrath more' anagrams to 'EARTHWORM'.
However, I'm not sure how the anagram is indicated.

'than' acts as a link.

Can you help me to learn more?

(Other definitions for earthworm that I've seen before include "What mole eats" , "One burrows" , "Garden burrower" , "Soil dweller" , "Soil-dwelling invertebrate" .)

I've seen this clue in The Irish Times.

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