Inspire everyone to overwhelm Welsh defence (8)

I believe the answer is:

firewall

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'defence' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'inspire everyone to overwhelm welsh' is the wordplay.
'inspire' becomes 'fire' (I've seen this in another clue).
'everyone' becomes 'all' (all people).
'to overwhelm' indicates putting letters inside.
'welsh' becomes 'W' (abbreviation).
'fire'+'all'='fireall'
'fireall' placed around 'w' is 'FIREWALL'.

Can you help me to learn more?

(Other definitions for firewall that I've seen before include "Computer security system against online attack" , "A protective system" , "network protection" , "Software protection for computer" .)

I've seen this clue in The Sunday Times and The Times.

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