To break off is less than to persevere (5)

I believe the answer is:

sever

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

'to break off' is the definition.
(I've seen this before)

'less than to persevere' is the wordplay.
'SEVER' is hidden within the letters.
However, I am uncertain how this is indicated.

'is' acts as a link.

Can you help me to learn more?

(Other definitions for sever that I've seen before include "Cut off suddenly" , "Verse (anag)" , "Divide, cut" , "Cut apart, maybe a relationship" , "Divorce" .)

I've seen this clue in the Evening Standard.

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