Deeply impressed by the impact (6)

I believe the answer is:

struck

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

'deeply impressed' is the definition.
'struck' can be an answer for 'impressed' (I've seen this before). I am unsure of the 'deeply' bit.

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for struck that I've seen before include "Walloped" , "set out" , "dismantled" , "Hit as by lightning" , "hit hard" .)

I've seen this clue in the Evening Standard.

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