Dull story in party with no end (7)
I believe the answer is:
relieve
'dull story in party with no end' is the definition.
'relieve' can be an answer for 'dull' (thesaurus). I'm unsure of the 'story in party with no end' bit.
'dull story in party with no end' is the wordplay.
'dull story' becomes 'lie' (story can mean a fabrication. I am not sure about the 'dull' bit.).
'in' is an insertion indicator.
'party' becomes 'revel' (I've seen this in another clue).
'with no end' means to remove the last letter.
'revel' with its final letter removed is 'reve'.
'lie' inserted into 'reve' is 'RELIEVE'.
Can you help me to learn more?
(Other definitions for relieve that I've seen before include "Make (pain) less severe" , "Alleviate (eg, pain)" , "Palliate" , "Allay, alleviate" , "Comfort" .)