Ant and Dec recycled old, boring, ultimately dire yarn (8)
I believe the answer is:
anecdote
'yarn' is the definition.
(I've seen this before)
'ant and dec recycled old boring ultimately dire' is the wordplay.
'and' means one lot of letters go next to another.
'recycled' indicates an anagram.
'old' becomes 'o' (abbreviation).
'boring' is an insertion indicator (some letters must 'bore' a hole into other letters).
'ultimately' indicates one should take the final letters.
The last letter of 'dire' is 'e'.
'ant'+'dec'='antdec'
'antdec' anagrammed gives 'anecdt'.
'anecdt' enclosing 'o' is 'anecdot'.
'anecdot'+'e'='ANECDOTE'
(Other definitions for anecdote that I've seen before include "Date once (anag.)" , "Humorous story" , "Short accoung of an incident" , "A short tale, usually true" , "Short account of an incident" .)