Convention recalled European Union limiting fuel supplies (5)
I believe the answer is:
usage
'convention' is the definition.
(I've seen this before)
'recalled european union limiting fuel supplies' is the wordplay.
'recalled' is a reversal indicator.
'european union' becomes 'eu'.
'limiting' is an insertion indicator.
'fuel supplies' becomes 'gas' (I can't justify this - if you can you should believe this answer much more).
'eu' placed around 'gas' is 'egasu'.
'egasu' backwards is 'USAGE'.
Can you help me to learn more?
(Other definitions for usage that I've seen before include "Interest of old" , "Common practice" , "Way of employing" , "Habitual custom" , "Silly little thing" .)