Solutions Not at one's best has 5 entries with similar clues

• 3-letter words
• manBest ... (groom's best friend, perhaps)
• 4-letter words
• aoneBest of the best
• 5-letter words
• anniecharles strouse and martin charnin show; 1977 tony award winner for best musical and best original score
• eliteBest of the best
• creamBest of the best