Hello OC,
my eye-sight isn't so good and couldn't zoom your image - but it looks like it might be part of an engine oil filler cap or similar. This looks like the part that goes through the centre and pulls the filler cap down clamping it shut into its filler neck. It has an action that when you pull the tab down the bolt pulls together (shortens) sandwiching the filler cap assembly, squeezinging an oil seal, expanding it into the filler neck and thus sealing the hole. Will look at work to see if I may have a complete unit picture...
Regards,
N1 Vibes