I do a lot of this sort of thing, and over the course of the last couple of years I've built solutions to a variety of problems into this program I call 'word'. The -a option asks for an anagram:

  % word -da tsju
  /^(?:(?=.*u)(?=.*s)(?=.*j)(?=.*t).{4,4})\z/oi
  just juts
  %
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but it can do many other things.

(Note that the program also assumes that this word-wrapper will be in the path, but that should be easy to hack out if not wanted.)

Hugo