Strong smell certainly rising – part of skeleton (7)
I believe the answer is:
humerus
'part of skeleton' is the definition.
'humerus' can be an answer for 'part' (humerus is a kind of part). I'm not sure about the 'of skeleton' bit.
'strong smell certainly rising' is the wordplay.
'strong smell' becomes 'hum' (something with a bad smell is 'humming'. I am not sure about the 'strong' bit.).
'certainly' becomes 'sure' (synonyms).
'rising' is a reversal indicator (in a down clue, letters go up).
'sure' back-to-front is 'erus'.
'hum'+'erus'='HUMERUS'
Can you help me to learn more?
(Other definitions for humerus that I've seen before include "Upper-arm bone" , "Bone that sounds funny?" , "Upper arm bone" , "Boneo of the upper arm" , "Bone from shoulder to elbow" .)