Prime Minister's pleased with jewel (9)
I believe the answer is:
gladstone
'prime minister's' is the definition.
(William Ewart Gladstone Prime Minister 1868-1894)
'pleased with jewel' is the wordplay.
'pleased' becomes 'glad' (similar in meaning).
'with' is a charade indicator (letters next to each other).
'jewel' becomes 'stone' (gem stone).
'glad'+'stone'='GLADSTONE'
(Other definitions for gladstone that I've seen before include "Former British prime minister and large travelling bag" , "Bag for a former British statesman" , "19th century PM" , "Old English P.M. or a doctor's bag" , "C. nineteenth Liberal prime minister" .)