Transparent finish behind still reflection (7)
I believe the answer is:
thought
'reflection' is the definition.
(I've seen this before)
'transparent finish behind still' is the wordplay.
'behind' indicates one should take the final letters.
'still' becomes 'ought' (I can't justify this - if you can you should believe this answer much more).
The last letters of 'transparent finish' are 'th'.
'th'+'ought'='THOUGHT'
Can you help me to learn more?
(Other definitions for thought that I've seen before include "Deliberated" , "Content of cognition" , "Philosopher must master this" , "Idea, concept" , "Supposed" .)