Thriller's first editions? They're disposable (7)
I believe the answer is:
tissues
'disposable' is the definition.
The definition and answer are not the same part of speech.
'thriller's first editions?' is the wordplay.
'thriller's first' becomes 't' (1st letter of 'thriller').
'editions?' becomes 'issues' (edition is a kind of issue).
't'+'issues'='TISSUES'
'they're' is the link.
Can you help me to learn more?
(Other definitions for tissues that I've seen before include "Paper hankies" , "Paper handkerchiefs" , "Thin skins or papers" , "Catchers, when suffering from cold" , "Sheets of very thin paper" .)