Each grasping MP here worried they'll not last long? (8)
I believe the answer is:
ephemera
'each grasping mp here worried they'll not last long?' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'each grasping mp here worried' is the wordplay.
'each' becomes 'ea' (abbreviation).
'grasping' is an insertion indicator (inserted letters are held or grasped).
'worried' indicates an anagram (worry can mean to interfere with or disturb).
'mp'+'here'='mphere'
'mphere' is an anagram of 'phemer'.
'ea' enclosing 'phemer' is 'EPHEMERA'.
Can you help me to learn more?
(Other definitions for ephemera that I've seen before include "Things lasting only briefly" , "Short-lived things of passing usefulness" , "Transitory things, lasting only a short time" , "Something transitory, lasting a day" , "of short span" .)