Player paid journalist to admit pamphlet's overlong (10)
I believe the answer is:
protracted
'overlong' is the definition.
(thesaurus)
'player paid journalist to admit pamphlet's' is the wordplay.
'player paid' becomes 'pro' (as opposed to an amateur).
'journalist' becomes 'ed' (short for editor).
'to admit' indicates putting letters inside.
'pamphlet' becomes 'tract' ('tract' can be a synonym of 'pamphlet').
'pro'+'ed'='proed'
'proed' going around 'tract' is 'PROTRACTED'.
(Other definitions for protracted that I've seen before include "Lengthened out" , "Dragged out" , "Drawn-out" , "Lengthy" .)