I made pear mincemeat last summer, mostly pears and raisins. Made the pie for Xmas. It is good but lacks a unifying base. Ideas? Thickener & molasses?

Thanks! But I'm still going for more than just cohesion; there is just some unifying flavor component that is missing. The "umami" mentioned earlier is getting close.

i would sprinkle cornstarch on the mincemeat and stir to combine. That should hold it together while cooking.

We have a pear tree that had a great year, hence the pear rather than apple. Otherwise, standard recipe with sugar (not overwhelming), citrus, spices and brandy. Recipe lacked suet; I added butter at cook time (which I don't normally add to pies but thought it might work with this recipe).
I am not searching for authenticity; thanks for asking. I'm hoping not to get into a back-and-forth with folks about tradition vs reinvention. Whatever it should be called, this fruit mince pie is made without beef and suet, which does leave a flavor gap. In chemistry, this would be more of a mixture than a compound, and I am looking for a compound.
(Was thinking a modest amount of a clearjell thickener to give illusion of cohesive filling.)

Not sure, not having seen your pear recipe.
Suggest you avoid thickener (if by that you mean flour) as it will muddy the taste of the mincement.
You could try the molasses for more sweet taste, but it won't thicken the whole, and it's a very American taste in a very British dish (if that matters to you).
I suggest you compare your recipe to one from a reliable British source (suggestions: BBC Good Food, Jamie Oliver, Delia Smith). Then add somethings from their recipes that weren't in yours.
I'm guessing suet, brown sugar, citrus zest and/or brandy will help.