One observes contrary directions in Mozart's quartet (6)
I believe the answer is:
viewer
'mozart's quartet' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'one observes contrary directions' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'i' (Roman numeral) and 'i' is present in the answer.
'directions' could be 'ewe' (I've seen this before) and 'ewe' is found within the answer.
This may be the basis of clue (or it may be nonsense).
'in' is the link.
Can you help me to learn more?
(Other definitions for viewer that I've seen before include "One who watches, say, TV" , "One watching, eg, TV" , "Review for TV watcher" , "One seeing" , "Observer" .)