Pam's disco dancing is jerky (9)
I believe the answer is:
spasmodic
'is jerky' is the definition.
(synonyms)
'pam's disco dancing' is the wordplay.
'dancing' is an anagram indicator.
'pams'+'disco'='pamsdisco'
'pamsdisco' is an anagram of 'SPASMODIC'.
(Other definitions for spasmodic that I've seen before include "fitfully" , "Intermittent" , "Occasional" , "Done in brief irregular bursts" , "Done in short bursts" .)