Flyer showing ale left accidentally (7)
I believe the answer is:
leaflet
'flyer' is the definition.
(I've seen this in another clue)
'ale left accidentally' is the wordplay.
'accidentally' is an anagram indicator (a chaotic or accidental ordering of the letters).
'ale'+'left'='aleleft'
'aleleft' is an anagram of 'LEAFLET'.
'showing' is the link.
(Other definitions for leaflet that I've seen before include "Handbill, flyer" , "Bill, pamphlet" , "Publication on single sheet" , "Single printed sheet" , "Distribute small circulars" .)