Had spread out, as did the former lining (7)
I believe the answer is:
dilated
'had spread out' is the definition.
The answer and definition can be both related to change as well as being past participle verbs.
Maybe there's a link between them I don't understand?
'did the former lining' is the wordplay.
'the former' becomes 'late' (late can mean former or previous).
'lining' indicates putting letters inside.
'did' going around 'late' is 'DILATED'.
'as' is the link.
Can you help me to learn more?
(Other definitions for dilated that I've seen before include "Made more open/wide" , "Enlarged" , "Spoke at length" , "like pupils in the dark" , "Became more open" .)