Hoop-shaped unit and curl-shaped interior of motor (8)
I believe the answer is:
circular
'motor' is the definition.
Both the definition and answer are adjectives. Perhaps they are linked in a way I don't understand?
'hoop-shaped unit and curl-shaped interior' is the wordplay.
'hoop-shaped' becomes 'car' (I can't explain this - if you can you should believe this answer much more).
'unit' becomes 'I' (resembles c, a unit).
'and' says to put letters next to each other.
'shaped' is an anagram indicator.
'interior' is an insertion indicator.
'i' after 'curl' is 'curli'.
'curli' is an anagram of 'ircul'.
'car' going around 'ircul' is 'CIRCULAR'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for circular that I've seen before include "Letter or notice copied to a number of people" , "Perfectly round" , "One sort of saw" , "Leaflet for mass distribution" , "Widely-distributed notice" .)