Computer's speed made concert a failure (8)
I believe the answer is:
gigaflop
'computer's speed' is the definition.
I know nothing about this answer so I can't judge whether this works.
'concert a failure' is the wordplay.
'concert' becomes 'gig' (I've seen this in another clue).
'failure' becomes 'flop' (flop is a kind of failure).
'gig'+'a'+'flop'='GIGAFLOP'
'made' is the link.
Can you help me to learn more?
(Other definitions for gigaflop that I've seen before include "PDQ, relatively speaking" , "Massive calculation" , "Speed of computer operation" .)