We dined perhaps and swelled out (7)
I believe the answer is:
widened
'swelled out' is the definition.
The definition and answer can be both related to change as well as being past participle verbs.
Maybe they are linked in a way I don't understand?
'we dined perhaps' is the wordplay.
'perhaps' is an anagram indicator.
'we'+'dined'='wedined'
'wedined' with letters rearranged gives 'WIDENED'.
'and' is the link.
Can you help me to learn more?
(Other definitions for widened that I've seen before include "Expanded" , "Made broader" , "Given more breadth" .)