An element of the police force? (6)
I believe the answer is:
copper
This might be a double definition.
'an element' is the first definition.
(copper is a kind of element)
'police force?' is the second definition.
'copper' can be an answer for 'police' (thesaurus). I am unsure of the 'force?' bit.
'of the' is the link.
Can you help me to learn more?
(Other definitions for copper that I've seen before include "Small loose change" , "bluebottle" , "Little money" , "Red-brown metal" , "A little cash" .)