The title of this article says,
UK Prime Minister Johnson to declare Britain can end 'the groundhoggery' of Brexit
So there was no entry in the dictionary nor googling didn't help.
I suspect the word is the combination of the noun "ground" and the verb "hog", defined at 5a or b?
1 : to cut (a horse's mane) short : roach
2 : to clean the bottom of (a ship) with a hog
3 a : to cause to arch like the back of a hog b : to cause (as a ship or timber) to bow up in the middle and sag at the ends usually as a result of improper loading or supporting
4 a British : to winter over (young sheep) b : to utilize (an unharvested crop) by turning in hogs to feed — often used with down or off
5 a : to take, grasp, or retain selfishly or in excess of one's due or need b : to consume voraciously — usually used with down
6 : to play (a curling stone) so as not to pass the hog score
7 : to tear up or shred (bulk material) into bits with a hog
intransitive verb 1 : to become curved upward in the middle like a hog's back — used especially of a ship or its bottom or keel 2 : to act like a hog especially in taking more than one's share
meaning (Johnson's going to stop) people voraciously dig into this matter too much, would it?