Muddle keeps right one in complex romantic situation (8)
I believe the answer is:
triangle
'complex romantic situation' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'muddle keeps right one' is the wordplay.
'muddle' becomes 'tangle' (I can't explain this - if you can you should give a lot more credence to this answer).
'keeps' is an insertion indicator.
'right' becomes 'r' (common abbreviation).
'one' becomes 'I' (Roman numeral).
'r'+'i'='ri'
'tangle' going around 'ri' is 'TRIANGLE'.
'in' is the link.
Can you help me to learn more?
(Other definitions for triangle that I've seen before include "Simple percussion instrument" , "Constellation - three-sided figure" , "Regular shape with" , "Polygon, could be isosceles" , "Three-sided percussion instrument" .)