Fun grid. Thanks. Refit group has two nouns and two verbs so they do not marry neatly. I would personally give another explanation to the messes group to suggest what links them all as an action - people probably won't guess your answer.

And caps are not necessary

easy grid to see the groups but difficult to guess what the creator has put as the acceptable answer.

the trifles group would be better described as synonyms as these words can precede many others.
the refit group changed tense which made the connection weak I think.
the grid otherwise worked well though and I enjoyed it