Joke with one wearing raincoat like a king? (8)
I believe the answer is:
majestic
'like a king?' is the definition.
'joke with one wearing raincoat' is the wordplay.
'joke' becomes 'jest' (synonyms).
'with' is a charade indicator (letters next to each other).
'one' becomes 'i' (Roman numeral).
'wearing' means one lot of letters goes inside another.
'raincoat' becomes 'mac' (mac is a kind of raincoat).
'jest'+'i'='jesti'
'jesti' placed within 'mac' is 'MAJESTIC'.
(Other definitions for majestic that I've seen before include "Impressively beautiful" , "Regal - grand" , "Splendid, regal" , "Regal, imperial" , "Stately, dignified or grand" .)