Depending on what level clearance you are talking about, you will be asked to document a lot of your past professional and personal history. You will need to provide references for your character and your past jobs, and finding people who are cooperative may be trickier than you think.
Do you like to travel?
You may need to provide advance notice if you travel outside of the country.
Do you enjoy polygraphs?
I've manage to sidestep this one myself, but I'm told that lie detector tests are not fun.
On the plus side, having a clearance opens a lot of well-paying stable job opportunities.
On the plus side, you can duplicate references, so if you had a constant roommate just put them down.
Polygraphs won't apply to what's presumably a basic security clearance. There's a large cost to clearances and they won't get maximum clearance for an intern.
Depending on how long it takes to get your clearance, you may only have an interim clearance during your internship. This is probably for the employer to cover themselves if you encountered any sensitive information. It's highly unlikely you will be working with sensitive information, unless you go back to intern with them in the future.
One benefit of security clearances is that it is transferable, and is good for 2 years after you leave the job (without having to reapply). So you could intern, get a clearance, intern somewhere else next year, and then get a job after graduation that requires a clearance. If you're interested in certain aerospace or defense companies, this is a plus for them.
I got one years ago, but civil (government). I found it odd I was asked about my grandparents' occupations. No harm came.
Large companies, particularly those in finance, also ask for clearance which they also call security clearance. That's mainly ensuring a clean track record. One big area that I've seen people mess up is 'Directorships'. Having once registered a company, and keeping that company running, is a directorship, even if the company is idle. It takes a lot of unwinding with HR and audit when these things that are often only sometimes checked, or an international check is not run. Do declare directorships; as long as there is no conflict of interest there's noting to worry about, and if there is a conflict of interest, get it in the open because you could be accused of criminal liability.
- Requirement to disclose any travel plans outside of US.
- Forbidden to have dual citizenship.
- Requirement to disclose relationships (even non-professional) with foreign nationals.
I suppose that's necessary, but it's embarrassing. Calling your friends ahead of time to give them a heads-up would be something I'd think about doing.
Clearances cost a lot of money, but you never have to pay the money or even know how much it is. It's a license to get exclusive well-paying jobs.