Media pack finding old service provider (5,4)
I believe the answer is:
press gang
'old service provider' is the definition.
(group forcing people into the armed services)
'media pack' is the wordplay.
'media' becomes 'press' (the press is part of the media).
'pack' becomes 'gang' (synonyms).
'press'+'gang'='PRESS-GANG'
'finding' acts as a link.
(Other definitions for press gang that I've seen before include "journalists?" , "Old navy recruiting body" , "Body forcibly enlisting" , "Forcible recruiting agents" , "Force into service" .)