Message that was sent with passion (4)
I believe the answer is:
wire
'message that was sent' is the definition.
'with passion' is the wordplay.
'with' becomes 'w' (abbreviation).
'passion' becomes 'ire' (I've seen this before).
'w'+'ire'='WIRE'
(Other definitions for wire that I've seen before include "Thin drawn metal" , "Thin strip of metal, may be barbed" , "See 20" , "Flexible strands of metal" , "Strand of metal" .)