Tins opened by retired islanders (7)
I believe the answer is:
cretans
'islanders' is the definition.
The definition and answer can be both people as well as being plural nouns.
Maybe you can see a link between them that I can't see?
'tins opened by retired' is the wordplay.
'tins' becomes 'cans' ('can' can be a synonym of 'tin').
'opened by' is an insertion indicator (some letters open a gap in others).
'retired' becomes 'ret' (e.g. following the name of a retired army officer).
'cans' placed around 'ret' is 'CRETANS'.
Can you help me to learn more?
(Another definition for cretans that I've seen is " These islanders".)