Show possibly entertains with endless pop (12)
I believe the answer is:
presentation
'show' is the definition.
(I've seen this before)
'possibly entertains with endless pop' is the wordplay.
'possibly' indicates anagramming the letters.
'with' means one lot of letters go next to another.
'endless' means to remove the last letter.
'pop' with its last letter taken off is 'po'.
'entertains'+'po'='entertainspo'
'entertainspo' is an anagram of 'PRESENTATION'.
(Other definitions for presentation that I've seen before include "Display" , "show" , "Formal introduction" , "when gifts are handed out?" , "Illustrated formal talk" .)