Ruined when a bit of fun's all over? (6)
I believe the answer is:
undone
'ruined' is the definition.
(I know that ruined can be written as undone)
'when a bit of fun's all over?' is the wordplay.
'when' becomes 'on' (I've seen this in other clues).
'a bit of fun's' becomes 'unde' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'all over?' means one lot of letters goes inside another.
'on' going into 'unde' is 'UNDONE'.
Can you help me to learn more?
(Other definitions for undone that I've seen before include "Unfastened or brought to ruin" , "Brought to ruin or destruction - or not buttoned" , "Not bound" , "Brought to ruin or buttons not fastened" , "Opened" .)