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' means one lot of letters go next to another (in a down clue, letters appear on others).
'a reduced diet' becomes 'et' (I can't justify this - if you can you should give a lot more credence to this answer).
'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" .)