Solutions Ill-use has 5 entries with similar clues

• 4-letter words
• neonNoble gas used in illuminated signs
• 6-letter words
• op-artA form of abstract art that gives the illusion of movement by its use of pattern and colour
• 7-letter words
• sweatedOf labour ill-treated and ill-paid
• 10-letter words
• case-studyA particular instance used to illustrate a general principle
• 16-letter words
• anabolic-steroidA synthetic hormone used to promote muscle growth and illegally enhance performance