Own goal to include Republican article in periodical (5)
I believe the answer is:
organ
'periodical' is the definition.
(organ is a kind of periodical)
'own goal to include republican article' is the wordplay.
'own goal' becomes 'og' (football abbreviation).
'to include' indicates putting letters inside.
'republican' becomes 'r' (abbreviation).
'article' becomes 'an' (indefinite article).
'og' going around 'r' is 'org'.
'org'+'an'='ORGAN'
'in' is the link.
(Other definitions for organ that I've seen before include "Instrument with stops" , "specialist magazine" , "Word after "pipe" or "barrel"" , "Functional part of body" , "House journal" .)