Enter a clue or pattern or both:
The Clue
Litmus is one kind (4 letter answer)
The Answer
TEST
Tags
Notes
The answer TEST is seen frequently, appearing about once every 60 puzzles.
Related Clues
Assay
Audition
Check
Criterion
Exam
Experiment
Midterm, for one
Quiz
S.A.T., for one
Schick ___
Touchstone
Trial
Try
Acid or high
Check out
Dick or Schick
Dry run
Final, e.g.
Give a whirl
Invertebrate shell
Kind of tube
Lab job
Lab procedure
Lab routine
Midterm event
Midterm, say
Put to proof
S.A.T., e.g.
SAT, e.g.
Try out
Use a cupel
Consumer Reports report
Entrance requirement, maybe
Market-research tool
Step in getting a license