Dancing and having a good time on a reduced diet (6)
I believe the answer is:
ballet
'dancing' is the definition.
(ballet is a kind of dancing)
'good time on a reduced diet' is the wordplay.
'good time' becomes 'ball' (I've seen this in another clue).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'a reduced diet' becomes 'et' (I am not sure about this - if you are sure you should believe this answer much more).
'ball'+'et'='BALLET'
'and having a' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for ballet that I've seen before include "Classical dancing style" , "Theatrical dance" , "Dance art form" , "old madrigal" , "kind of skirt" .)