Weakling died, rest well (4)
I believe the answer is:
drip
'weakling' is the definition.
(thesaurus)
'died rest well' is the wordplay.
'died' becomes 'd' (abbreviation next to the year of someone's death).
'rest well' becomes 'rip' (I can't justify this - if you can you should give a lot more credence to this answer).
'd'+'rip'='DRIP'
Can you help me to learn more?
(Other definitions for drip that I've seen before include "Fall from a leaking tap - weakling" , "Ineffectual person; hospital apparatus" , "Splash - softie" , "Fall in small drops as from tap" , "Fall in small amounts" .)