"Nicely Kept": Compound Word or Phrase?

"Nicely kept" is not a compound word. It is a phrase consisting of:

• Nicely – adverb (modifies the participle)
• Kept – past participle of "keep" (functioning as an adjective)

Compound words are single lexical units (e.g., "well-kept" with a hyphen). "Nicely kept" remains two separate words.