A singer behind bars (6)
I believe the answer is:
canary
'a singer' is the definition.
(canary is a kind of birdanimal)
'behind bars' is the wordplay.
'behind' becomes 'can' ('can' can be a synonym of 'behind').
'bars' becomes 'ary' (I am not sure about this - if you are sure you should believe this answer much more).
'can'+'ary'='CANARY'
Can you help me to learn more?
(Other definitions for canary that I've seen before include "Bird from an island group" , "Bright yellow finch" , "Yellow bird, formerly taken down mines" , "grass" , "a sort of finch" .)