Brain teaser

Group A
Lonely
Patent
Canines
Freighter
Artwork

Group B
Local Election
News Event
Tax Return
Brainy Teaser
Play Date

Look over Group A closely, then decide which entry from Group B belongs in Group A...

Okay, here's the answer.

The answer is "News Event"

Why, you ask?

Because each of the words in Group A had a number in it.

lONEly
paTENt
caNINEs
frEIGHTer
arTWOrk

So, of course, you have newS EVENt to add to it.