Deleting part of a cell if it doesn't contain required data

I have a string containing upto 200 words separated by a comma. I would like to be able to delete the words that don't contain the first 3 letters that match a 3 letter word in a different cell on the same row.

I have upto 10,000 rows with these types of string on them.

I have attached a mock up of what I mean, the green coloured cells are the ones that I want to remain on column b and the red ones are those which I want to delete.

Can anyone suggest anything please?