Old man keeping almost slow and square (5)
I believe the answer is:
plaza
'square' is the definition.
(I know that square can be written as plaza)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for plaza that I've seen before include "Public square, as in Spanish town" , "Hotel" , "open space" , "The ____ Mayor is important in Madrid" , "Open square in Spain" .)