Banker describes partners as extremely stupid (5)
I believe the answer is:
dense
'extremely stupid' is the definition.
'dense' can be an answer for 'stupid' (similar in meaning). I am not sure about the 'extremely' bit.
'banker describes partners' is the wordplay.
'banker' becomes 'dee' (I've seen this in other clues).
'describes' is an insertion indicator (describe can mean to form the outline of).
'partners' becomes 'ns' (North and South are partners in the game bridge).
'dee' going around 'ns' is 'DENSE'.
'as' acts as a link.
Can you help me to learn more?
(Other definitions for dense that I've seen before include "Solid, thick" , "Closely spaced or extremely stupid" , "Thick and tightly-packed" , "Closely-spaced" , "Closely crowded together" .)