Irrational cares can be alarming (5)

I believe the answer is:

scare

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

'be alarming' is the definition.
I can't judge whether this defines the answer.

'irrational cares' is the wordplay.
'irrational' indicates an anagram.
'cares' with letters rearranged gives 'SCARE'.

'can' is the link.

Can you help me to learn more?

(Other definitions for scare that I've seen before include "Cause fright, alarm" , "Panic" , "Frighten, alarm" , "Health worry" , "Frighten or intimidate" .)

I've seen this clue in the Evening Standard.

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