I'd made design for crown (6)
I believe the answer is:
diadem
'for crown' is the definition.
(synonyms)
'i'd made design' is the wordplay.
'design' is an anagram indicator.
'id'+'made'='idmade'
'idmade' anagrammed gives 'DIADEM'.
(Other definitions for diadem that I've seen before include "Regal power" , "Crown or headband for sovereign" , "Royal headdress" , "Crown or headband worn as sign of sovereignty" , "Crown or headband worn as symbol of sovereignty" .)