Replacing this compiler with uniform rubbish would be swell (5)
I believe the answer is:
bulge
'be swell' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for bulge that I've seen before include "Battle of the -----: last major German counter-offensive of WWII (1944)" , "Rounded swelling" , "Protuberance or outward swelling" , "Hitler's offensive" , "Swelling - sudden increase" .)