Clegg felt the Portman Road club had little option but to accept the bid for the 18-year-old frontman.
"When offers on the table all of a sudden exceed what you believe the player is worth, at this particular moment in time, then you have to act," he told the Ipswich Evening Star.
"You also have to take into account what you could do with the additional money.
"Negotiations had been going on for some time, and we had serious interest from Sunderland for the last week or 10 days.
"The result is that we have a cracking deal for Ipswich Town. I'm very pleased with it. And it's a good move for Connor as well. In fact, it's an historic day for the football club."