Long story entertains beginning to end (5)
I believe the answer is:
yearn
'long' is the definition.
('yearn' can be a synonym of 'long')
'story entertains beginning to end' is the wordplay.
'story' becomes 'yarn' ('yarn' can be a synonym of 'story').
'entertains' means one lot of letters goes inside another.
'beginning to' indicates taking the first letters.
The first letter of 'end' is 'e'.
'yarn' placed around 'e' is 'YEARN'.
(Other definitions for yearn that I've seen before include "lust" , "Have a craving" , "Pant - pine" , "Desire, want" , "Ache, crave" .)