by Charles Steinhardt and Robin Baur
The acrosses and downs cannot be filled into a 10 by 10 grid, but can be filled into a 21 by 21 grid with many black squares, if one square is allowed to contain "START" and another "END".
Taking every other letter in the 21 by 21 grid, we get a complete 10 by 10 grid (like the blank one given), where boundaries sometimes have a letter at them.
We interpret this as a maze, and find the unique solution from START to END.
The letters along the solution path spell out HONORVERSE STAR KINGDOMS OR PERSIAN MARTYAXWARS, cluing MANTICORES.
Answers to the clues:
Overactor; Frasier role; lip hair, briefly
Northwestern state; louder; venomous Indian snake
Home canners; heron, in Munich
Cautious and deliberate; adventurous acts
Foundation author; make unwanted comments; type of salt
Pallid; prized; Roman galley
Declare unfit for habitation; thinking machines (abbr.); discard
Former, as a girlfriend; collection of Persian quatrains; Ken's gal
Provide with weapons; whirlpool; sorcerer
Mule's daddies; Welsh dish
Religious school; Amend strip
Village People tune; part of a musical note; marital invalidation
Adhere to a surface; Norwegian attractions; angled edge
Celebration before Lent; osso buco component; Joan of Arc, for example
Pollux or Betelgeuse; part of an oarlock; Menlo Park denizen; eight bits; transmit
Owner of a Lonely Heart band; items for a book collector; machines found at a car wash
Theater aide; snitch; Argentine repression
Stirring up, as a fire; inferior substitutes
Pumbaa, for example; Chef's garment; certain spiritual leader
Societies simpler than a state; sub-par result?