Fits up local employed by the opticians (6)
I believe the answer is:
frames
'fits' is the definition.
The definition and answer can be both to do with fundamental existence as well as being verbs in their -s form.
Perhaps there's an association between them I don't understand?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for frames that I've seen before include "Supporting or surrounding structures" , "Borders, around pictures say" , "Rounds of snooker play, or spectacles structures" .)