Related Clues:

• Tied up in knots
• It can be past or present, in grammar
• Verb form
• Grammar concern
• Far from laid-back
• Form of a verb
• Unable to relax
• Tested, in a way
• Wore out
• Hardly harmonious
• Nervous as a cat
• Grammatical time setter
• Temporal language element
• Pluperfect, for one
• Past, for instance