Place kiss on girl's chest (6)
I believe the answer is:
'girl's chest' is the definition.
'thorax' can be an answer for 'chest' (synonyms). I'm not certain of the 'girl's' bit.
'place kiss on' is the wordplay.
'place' becomes 'thora' (I can't explain this - if you can you should believe this answer much more).
'kiss' becomes 'x' (X can represent a kiss).
'on' says to put letters next to each other.
Can you help me to learn more?
(Other definitions for thorax that I've seen before include "Part of the body containing 3" , "Between the neck and belly" , "Part of the body between the head and abdomen" , "Part of the human torso between neck and diaphragm" , "Chest" .)