Perennial list must include fuel regularly (5)
I believe the answer is:
tulip
'perennial' is the definition.
(tulip is a type of perennial plant)
'list must include fuel regularly' is the wordplay.
'list' becomes 'tip' (both can mean to lean or incline).
'must include' is an insertion indicator.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
The alternating letters of 'fuel' are 'ul'.
'tip' going around 'ul' is 'TULIP'.
(Other definitions for tulip that I've seen before include "Bulb producing a single showy flower" , ""Dutch" flower" , "cause of mania once" , "... and another [FLOWER]" , "Bulbous plant" .)