Possible Clues:

• They're responsible for split sides but firm middles
• New-style cinemas do such entertainers
• First to arrive and is then mixed-up in a funny sort of way
• Come before I had come up with the answer - funny isn' it?
• Funny how they'd arrive at it before I'd come up with the short answer
• They have a funny way to arrive at what belongs to Diana
• Funny how they arrive before I would at the short answer
• Some stand-up characters of Greene
• Funny way they have to get to the start of 9 across to begin with
• Funny how they arrive with one in the sand (9)