Possible Clues:

• Lethargic — drop it (anag)
• Peak before rising depression renders you sleepy
• From south, would I protect bears hibernating?
• Slow-moving peak and hollow converge to the centre
• Sluggish swim with rubbish around
• Dull Conservative nearly given money to withhold article
• Sluggish swim, rubbish doing the backstroke?
• Dormant; passive
• In biology, being in a condition of suspended animation
• Lethargic duck turned around behind hill