Crossword Genius

Foe had run into unprecedented difficulty (7-2)

Ross

I believe the answer is:

unheard-of

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

'into unprecedented difficulty' is the definition.
I can't judge whether this defines the answer.

'foe had run' is the wordplay.
'foe had run' anagrams to 'UNHEARD-OF'.
However, I'm unsure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for unheard-of that I've seen before include "Without precedent" , "Previously unknown" , "Inconceivable" , "Not previously known or done - inaudible?" , "Unknown - novel" .)

I've seen this clue in The Globe and Mail.
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