Dance erratically, collapsing after taking pills (5)
I believe the answer is:
conga
'dance' is the definition.
(I've seen this before)
'erratically collapsing after taking pills' is the wordplay.
'erratically' indicates an anagram.
'after taking' indicates named letters should be taken away.
'collapsing' with 'pills' removed is 'coang'.
'coang' anagrammed gives 'CONGA'.
(Other definitions for conga that I've seen before include "Serpentine dance" , "wiggling line" , "Party dance" , "Latin American "follow-my-leader" dance" , "Circuitous line dance" .)