Pawnbroker practically accepted on old square (6)
I believe the answer is:
uncool
'square' is the definition.
(I've seen this in another clue)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for uncool that I've seen before include "hot?" , "Not in fashion or with it" , "Old-fashioned" , "Not with it (but warm?)" , "Not fashionable (colloq.)" .)