Sleeper separators consisting of wrought iron caps in hollow train bases (4,4)
I believe the answer is:
twin beds
'sleeper separators consisting of wrought iron caps' is the definition.
I can't judge whether this definition defines the answer.
'hollow train bases' is the wordplay.
'hollow train' becomes 'twin' (I can't explain this - if you can you should give a lot more credence to this answer).
'bases' becomes 'beds' (bed is a kind of base).
'twin'+'beds'='TWIN BEDS'
'in' is the link.
Can you help me to learn more?
(Another definition for twin beds that I've seen is " Bedroom furniture for two".)