Sausage made by pioneer’s fantastic, very soft inside (9)
I believe the answer is:
pepperoni
'sausage' is the definition.
(I've seen this before)
'pioneer's fantastic very soft inside' is the wordplay.
'fantastic' is an anagram indicator.
'very soft' becomes 'pp'.
'inside' is an insertion indicator.
'pioneer' anagrammed gives 'peeroni'.
'peeroni' placed around 'pp' is 'PEPPERONI'.
'made by' is the link.
(Other definitions for pepperoni that I've seen before include "what may be called a banger" , "spicy food" , "Hard, spicy beef and pork sausage" , "Spicy salami" , "Highly-seasoned sausage" .)