Single entry brings joy (4)
I believe the answer is:
glee
'joy' is the definition.
(I've seen this before)
'single entry brings' is the wordplay.
'brings' says the answer is hidden in the clue (I've seen 'bringing' mean this).
'GLEE' is hidden in the letters of 'single entry'.
(Other definitions for glee that I've seen before include "Lively or triumphant joy" , "Sort of club" , "Mirth - part-song" , "Great joy" , "Part-song for male voices - delight" .)