Ungodliest, harrowing: together they circle the world (10)

I believe the answer is:

longitudes

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

'world' is the definition.
Although both the answer and definition are nouns, they are not in the same form of the noun.

'ungodliest harrowing together they circle' is the wordplay.
'ungodliest' anagrams to 'LONGITUDES'.
However, I'm not clear how the anagram is indicated.

'the' acts as a link.

Can you help me to learn more?

I've seen this clue in The Everyman puzzle in The Observer.

Want a hint initially instead of a full solution? Install my app