They are never going to say to vote tactically but resources will be targeted at constituencies where they stand a good chance of winning, which will have a similar effect. I'd respect them more if they said "we aren't going to win in X, so vote Lib Dem/Green/SNP to really stick the boot in" as it might make all the difference.
The thing about Clacton is polling suggests Labour are in second, with Farage well ahead. So an argument could be made for Labour to step it up a gear there because if Farage messes up (perhaps by continuing to be a Putin stooge) they could sneak between a split Tory/Reform vote and get a cheeky win. Anything to keep Farage out of Parliament as his influence is corrosive. They may be calculating that Farage as an MP might be the nail in the Tory's coffin for a generation but it may bite them in the arse.