Pork pie stuffed with bit of nougat's rank (4)
I believe the answer is:
line
'rank' is the definition.
(thesaurus)
'pork pie stuffed with bit of nougat's' is the wordplay.
'pork pie' becomes 'lie' ('pork pie' is Cockney rhyming slang for a lie).
'stuffed with' means one lot of letters goes inside another (some letters get stuffed inside).
'bit of' indicates taking the first letters.
The initial letter of 'nougats' is 'n'.
'lie' going around 'n' is 'LINE'.
(Other definitions for line that I've seen before include "A length without breadth or thickness" , "Wrinkle; row" , "short note" , "column" , "cover on the inside" .)