Shakespearean character's endless boom ... (7)
I believe the answer is:
prosper
'boom' is the definition.
(synonyms)
'shakespearean character's endless' is the wordplay.
I cannot really understand how this works, but
'character's' could be 'os' and 'os' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for prosper that I've seen before include "Do well, be successful in life" , "Make good" , "Thrive, boom" , "Get rich" , "Succeed, flourish" .)