Sick about the lady ending a romantic interlude (5)
I believe the answer is:
'a romantic interlude' is the definition.
(I've seen this in another clue)
'sick about the lady ending' is the wordplay.
'sick' becomes 'ill' (similar in meaning).
'about' is an insertion indicator.
'the lady ending' becomes 'dy' (I am not sure about this - if you are sure you should believe this answer much more).
'ill' enclosing 'dy' is 'IDYLL'.
Can you help me to learn more?
(Other definitions for idyll that I've seen before include "Perfect situation" , "Poem descriptive of pastoral life" , "Blissful situation" , "Romantic scene or incident in country life" , "Poem - charming scene" .)