Bread roll using the French gas up (5)
I believe the answer is:
bagel
'bread roll' is the definition.
(I've seen this in another clue)
'the french gas up' is the wordplay.
'the french' becomes 'le' ('the' in French).
'gas' becomes 'gab' (I am not sure about this - if you are sure you should believe this answer much more).
'up' is a reversal indicator (in down clue: letters go upwards).
'le'+'gab'='legab'
'legab' back-to-front is 'BAGEL'.
'using' is the link.
Can you help me to learn more?
(Other definitions for bagel that I've seen before include "Doughnut-shaped bread roll" , "It's edible" , "round fare" , "Ring-shaped bread product" , "Jewish baked roll" .)