Is there an easy way to do this? On Aptana I used Control+click and I wish there was a way to do something similar on Atom.
The functionality is already present in atom via the Symbols View package you don't need to install anything.
The command you are searching for is symbols-view:go-to-declaration (Jump to the symbol under the cursor) which is bound by default to cmd-alt-down on macOS and ctrl-alt-down on Linux.
just note that it will work only if you will have generated tags for your project, either via this package or via ctags (exuberant or not)