Opened a couple of letters to read (6)
I believe the answer is:
spread
'opened' is the definition.
Both the answer and definition are adjectives. Maybe you can see an association between them that I don't see?
'a couple of letters to read' is the wordplay.
'a couple of letters' can mean two replacements for 'letter'.
'letter' becomes 's'.
'letter' becomes 'p' ().
'to' is a charade indicator (letters next to each other).
's'+'p'+'read'='SPREAD'
Can you help me to learn more?
(Other definitions for spread that I've seen before include "we hope to avoid in middle age" , "butter?" , "Generous meal" , "Scatter around" , "Extend - banquet" .)