She can sing and moan terribly (7)
I believe the answer is:
madonna
'she' is the definition.
'and moan terribly' is the wordplay.
'terribly' indicates anagramming the letters.
'and'+'moan'='andmoan'
'andmoan' anagrammed gives 'MADONNA'.
'can sing' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for madonna that I've seen before include "Religious art subject - pop singer, b. 1958" , "Like a Virgin singer" , "American pop singer" , "Virgin Mary; singer" , "pop star" .)