one way ticket
 

A one way ticket to the US costs about 6 times the price of an economy return from initial enquiries.
Are there any implications using a return ticket to use one way only?

As long as you use the first segment first that will be fine.

If you wish, cancel your return booking a day or so before departure. They will inform you that it's not refundable etc., etc., and you simply confirm you understand that. If they ask why you're cancelling just say it's for personal reasons beyond your control. In reality you could do none of the above and just not turn up for the flight and there will be no repecussions (they have your money). Do not plan to use the return portion only. That will not work under any circumstances.

Thank you Hotel Tango