Not plain, I imagine (5)
I believe the answer is:
fancy
This clue could be a double definition.
'not plain' is the first definition.
(I know this)
'imagine' is the second definition.
(I know that fancy is a more specific form of the action imagine)
'i' is the link.
This may not be correct. It may belong to one of the definitions.
Can you help me to learn more?
(Other definitions for fancy that I've seen before include "Highly-decorated; whim" , "Imagine; complicated" , "Be crazy about" , "An ornamental whim?" , "Elaborate; whim" .)