"Fastener" is more analogous (6)
I believe the answer is:
closer
'analogous' is the definition.
Both the answer and definition are adjectives. Perhaps you can see an association between them that I don't see?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for closer that I've seen before include "More airless; nearer" , "More near or imminent" , "Nearer or meaner" , "Nearer in time or space" , "Stuffier" .)