Individual component houses key within clock (8)
I believe the answer is:
separate
'individual' is the definition.
'component houses key within clock' is the wordplay.
'component' becomes 'part' (a component is a part of something).
'houses' means one lot of letters goes inside another.
'key' becomes 'A' (musical key).
'within' means one lot of letters goes inside another.
'clock' becomes 'see' (clock can mean to see or realise).
'part' enclosing 'a' is 'parat'.
'parat' placed within 'see' is 'SEPARATE'.
(Other definitions for separate that I've seen before include "Take or keep apart" , "Distinct; divide" , "Divided or detached" , "Pull apart" , "Not joined or united with others" .)