Concealed inner parts of clocks' movement (6)
I believe the answer is:
occult
'concealed' is the definition.
(thesaurus)
'parts of clocks' movement' is the wordplay.
'parts' suggests taking the first letters (I've seen 'part' mean this).
'movement' becomes 'cult' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
The first letters of 'of clocks' is 'oc'.
'oc'+'cult'='OCCULT'
'inner' acts as a link.
This may not be right. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for occult that I've seen before include "Supernatural practices" , "Magical; hide from view (astron.)" , "Supernatural forces and events and beings" , "Involving magical powers" , "Mystical (black arts)" .)