In opera, she makes love between acts, madly! (5)
I believe the answer is:
tosca
'in opera she' is the definition.
The definition suggests a singular noun which matches the answer.
'love between acts madly' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'between' means one lot of letters goes inside another.
'madly' indicates anagramming the letters.
'acts' anagrammed gives 'tsca'.
'o' placed within 'tsca' is 'TOSCA'.
'makes' acts as a link.
Can you help me to learn more?
(Other definitions for tosca that I've seen before include "Coats off for a great opera" , "Photographic device" , "Puccini's Roman heroine" , "title role" , "musical work" .)