Rile Bert badly, causing great fear (8)

I believe the answer is:

terrible

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

'causing great fear' is the definition.
I can't judge whether this defines the answer.

'rile bert badly' is the wordplay.
'badly' indicates anagramming the letters (letters in the wrong order).
'rile'+'bert'='rilebert'
'rilebert' with letters rearranged gives 'TERRIBLE'.

Can you help me to learn more?

(Other definitions for terrible that I've seen before include "Atrocious" , "Appalling" , "Horrifying" , "Like tsar Ivan IV" , "Really bad" .)

I've seen this clue in The Telegraph.

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