Think tank

According to the dictionary a group of experts who are gathered to consider various problems and try to work out ways to solve them. I don't understand the context though.

it is used to describe a crowd of specialists / experts who get together to debate issues. This must mean that the think-tank in question is a bunch of economists who are in favour of a certain sort of trade

thanks Maj and Suzi

Here is anoher sentence with "think tank".

"....."said Edward, trade policy director at the Prograssive Policy Institute, a centrist Democratic think thank.

Does it has the same meaning?

The sentence "Economist, a pro-trade think tank, said he expected...." is grammatically incorrect. A think tank doesn't speak, and you wouldn't call one a "he".

The meaning of it is really difficult to understand.

the secong eg means the same

A think tank is simply a group of people who research issues and/or propose solutions. There are political think tanks, technology think tanks, military think tanks, etc.

I think it should be;
"Economist, a pro-trade think tank, said IT expected...."