Cube may impede progress (5)
I believe the answer is:
block
This clue could be a double definition.
'cube' is the first definition.
(synonyms)
'impede progress' is the second definition.
'block' can be an answer for 'impede' (blocking is a kind of impeding). I am unsure of the 'progress' bit.
'may' is the link.
Can you help me to learn more?
(Other definitions for block that I've seen before include "Jam" , "Solid lump" , "Cube" , "Impede, prevent" , "City area; prevent flow" .)