‘Corruption’ is a subtle word, because it describes a process rather than an event. It does not merely mean bad behaviour: it means behaviour that becomes rotten out of something which was once good. That is why it often afflicts high-minded organisations more than ordinary businesses. People who think they are collectively moral are more self-deceiving than the average market trader.
Hence the current embarrassments of the BBC about huge pay-offs. The reason that the Trust and executives are now publicly blaming each other over the issue is not because one side was in the wrong and the other in the right, but because, at the time, no one involved could see any serious problem with paying the equivalent of literally hundreds of thousands of annual television licence fees to top staff to go away.
The BBC was good; the executives were good; the departure of some of these good people was unfortunately necessary, and so they were paid good money in compensation. That is how it looked from the inside. Now they realise, too late, that it looks completely different from the outside. That difference of perception is how corruption starts.