Transparency islander lent freely (7,5)
I believe the answer is:
lantern slide
'transparency' is the definition.
(lantern slide is a kind of transparency)
'islander lent freely' is the wordplay.
'freely' indicates an anagram.
'islander'+'lent'='islanderlent'
'islanderlent' with letters rearranged gives 'LANTERN SLIDE'.
(Other definitions for lantern slide that I've seen before include "Former picture for projection" , "Former projection transparency" , "visual aid" , "Old transparency for projection" .)