Corrupt company mostly to regret ignoring a registration (9)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

Corrupt company mostly to regret ignoring a registration ENRO <n> (=corrupt company, from the US in the early 2000s; “mostly” means last letter is dropped) + L <a> MENT (=to regret, bemoan; “ignoring a ” means letter “a” is dropped)