Love quiet American musical work (4)
I believe the answer is:
opus
'musical work' is the definition.
(synonyms)
'love quiet american' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'american' becomes 'us' (abbreviation for United States).
'o'+'p'+'us'='OPUS'
(Other definitions for opus that I've seen before include "Piece of music (with number)" , "Work (mus.)" , "(Numbered) musical composition" , "Composer's catalogue number" , "A Latin work" .)