Engineers attack change from original design (5)
I believe the answer is:
refit
'change from original design' is the definition.
'refit' can be an answer for 'change' (thesaurus). I'm not certain of the 'from original design' bit.
'engineers attack' is the wordplay.
'engineers' becomes 're' (Royal Engineers).
'attack' becomes 'fit' (fit is a kind of attack).
're'+'fit'='REFIT'
Can you help me to learn more?
(Other definitions for refit that I've seen before include "Renovate (a ship)" , "restoration of ship" , "Equip by repairing or replacing parts" , "Do repair job" , "Replace ship's equipment" .)