Cause to like conclusion on organ (6)
I believe the answer is:
endear
'cause to like' is the definition.
(I've seen this before)
'conclusion on organ' is the wordplay.
'conclusion' becomes 'end' (something's conclusion is its end).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'organ' becomes 'ear' (the ear is an organ).
'end'+'ear'='ENDEAR'
(Other definitions for endear that I've seen before include "Make fond" , "Make beloved" , "Bind in gratitude" , "inspire love" , "Arouse affection" .)