Opening sounds in minor key (6)
I believe the answer is:
eyelet
'opening sounds in minor key' is the definition.
'eyelet' can be an answer for 'opening' (I've seen this before). I'm unsure of the 'sounds in minor key' bit.
'opening sounds in minor key' is the wordplay.
'opening' becomes 'eye' (eye is a kind of opening).
'sounds in minor key' becomes 'let' (I can't justify this - if you can you should believe this answer much more).
'eye'+'let'='EYELET'
Can you help me to learn more?
(Other definitions for eyelet that I've seen before include "One caught by hook" , "Small opening in shoe for lace" , "It is tiny place" , "Small reinforced hole" , "A lace is passed through it" .)