Slowly going round a sort of shed (4-2)
I believe the answer is:
lean-to
'sort of shed' is the definition.
'lean to' can be an answer for 'shed' (I've seen this before). I'm not sure about the 'sort of' bit.
'slowly going round a' is the wordplay.
'slowly' becomes 'lento' (musical instruction).
'going round' indicates putting letters inside (some letters go around others).
'lento' going around 'a' is 'LEAN-TO'.
Can you help me to learn more?
(Other definitions for lean-to that I've seen before include "Building added to another" , "Hut" , "Small building resting on side of larger one" , "Rough shelter lying against the wall of a building" , "Shed built onto house" .)