In Paris, I get fine on Metro regularly as someone selling trinkets (8)
I believe the answer is:
jeweller
'someone selling trinkets' is the definition.
(trinkets are a type of jewellery)
'in paris i get fine on metro regularly' is the wordplay.
'in paris i' becomes 'je' ('I' in French).
'get' says to put letters next to each other.
'fine' becomes 'well' (similar in meaning).
'on' is a charade indicator (letters next to each other).
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternating letters of 'metro' are 'er'.
'je'+'well'+'er'='JEWELLER'
'as' acts as a link.
(Other definitions for jeweller that I've seen before include "High street retailer" , "Gems he flogs" , "Tradesman" , "Dealer in precious stones and metal" , "Retailer in gemstone products" .)