Sounds like a passable romance (6)
I believe the answer is:
affair
'romance' is the definition.
(I've seen this before)
'sounds like a passable' is the wordplay.
'sounds like' becomes 'af' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a passable' becomes 'fair' (I've seen this before).
'af'+'fair'='AFFAIR'
Can you help me to learn more?
(Other definitions for affair that I've seen before include "Thing to be done with raffia" , "Liaison or intrigue" , "Former Belgian coin" , "Concern, matter or illicit romance" , "connected with love" .)