Over to last month’s design style (4)
I believe the answer is:
deco
'design style' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'over to last month's' is the wordplay.
'over' means one lot of letters go next to another.
'last' suggests the final letters.
'month' becomes 'dec' (Dec is an example).
The last letter of 'to' is 'o'.
'o' after 'dec' is 'DECO'.
Can you help me to learn more?
(Other definitions for deco that I've seen before include "Art -, C 20 style of ornamentation" , "Style of design popular in the 1920s and 1930s" , "Art's partner" .)