Longing for a boy with passion (6)
I believe the answer is:
desire
'longing' is the definition.
(I've seen this before)
'boy with passion' is the wordplay.
'boy' becomes 'des' (short for Desmond).
'with' says to put letters next to each other.
'passion' becomes 'ire' (ire is passionate anger).
'des'+'ire'='DESIRE'
'for a' acts as a link.
(Other definitions for desire that I've seen before include "Strong need" , "Covet" , "Want to reside?" , "Crave" , "Famous play: ''A Streetcar Named ......''" .)