Iron-based swings sound like suitable fairground attractions (6,6)
I believe the answer is:
ferris wheels
'sound like suitable fairground attractions' is the definition.
Although both the answer and definition are plural nouns, I cannot see how they can define each other.
'iron-based swings' is the wordplay.
I cannot quite see how this works, but
'iron' could be 'fe' (Fe is the chemical symbol for iron) and 'fe' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for ferris wheels that I've seen is " revolvers for entertainment?".)