Chaney-Lillian duet verging on excessive (7)
I believe the answer is:
longish
'duet verging on excessive' is the definition.
I can't judge whether this defines the answer.
'chaney-lillian' is the wordplay.
'chaney' becomes 'lon' (I've seen this in another clue).
'lillian' becomes 'gish' (I can't justify this - if you can you should give a lot more credence to this answer).
'lon'+'gish'='LONGISH'
Can you help me to learn more?
(Other definitions for longish that I've seen before include "Fairly extended" , "Fairly lengthy" .)