Helper of St Paul in eastern Tarsus, travelling (7)
I believe the answer is:
erastus
'helper of st paul' is the definition.
(associate of St Paul in the Bible)
'eastern tarsus travelling' is the wordplay.
'eastern' becomes 'e'.
'travelling' indicates anagramming the letters.
'tarsus' anagrammed gives 'rastus'.
'e'+'rastus'='ERASTUS'
'in' acts as a link.
(Other definitions for erastus that I've seen before include "theologian" , "opponent of Calvinism" , "Director of public works" .)