Unit of computer processing speed, for example, a failure after problem's back (8)

I believe the answer is:

megaflop

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'unit' is the definition.
(I know that megaflop is a type of unit)

'example a failure after problem's back' is the wordplay.
'example' becomes 'eg' (short for 'exempli gratia', 'for example' in Latin).
'failure' becomes 'flop' (flop is a kind of failure).
'after' means one lot of letters go next to another.
'back' indicates one should take the final letters (the letter at the back).
The last letter of 'problem' is 'm'.
'eg'+'a'+'flop'='egaflop'
'egaflop' put after 'm' is 'MEGAFLOP'.

'of computer processing speed for' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.

Can you help me to learn more?

(Other definitions for megaflop that I've seen before include "total disaster" , "Operations unit" , "total failure" .)

I've seen this clue in The Guardian.

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