An excellent program, available for free trial use, before registration of only $30 (simply pay with your UK credit card and download).
Allows import and export of clues and puzzles, built in thesaurus, fancy shaped crosswords, clues, bonus questions, etc.
I used this program for years. I foolishly left my registered version on an old discarded PC am determined to hunt it out and start using it again soon. It’s great for focusing on particular word endings or word strings, and parts of grammar. One of the most useful crosswords I produced with this was based on the past tense of verbs.