You can define mouse & key bindinds in .sublime-mousemap files
In your case, use this binding:
{"button": "button1", "count": 1, "modifiers": ["ctrl"],"press_command": "drag_select","command": "goto_definition"}
I would suggest to add the shift
modifier because CTRL + LEFT CLICK
is used for "multiple selection".
{"button": "button1", "count": 1, "modifiers": ["shift","ctrl"],"press_command": "drag_select","command": "goto_definition"}
Do no forget to wrap the bindings with [
and ]
(they are defined as a JSON array of objects)
Regards