Dizzy playing tunes on jazzy day (8)
I believe the answer is:
unsteady
'dizzy' is the definition.
(thesaurus)
'playing tunes on jazzy day' is the wordplay.
'playing' is an anagram indicator.
'on' means one lot of letters go next to another.
'jazzy' indicates anagramming the letters.
'tunes' with letters rearranged gives 'unste'.
'day' is an anagram of 'ady'.
'unste'+'ady'='UNSTEADY'
(Other definitions for unsteady that I've seen before include "not like rock" , "Rocky" , "Not even" , "Reeling" , "inconstant" .)