Fuel to rise and sink (3)
I believe the answer is:
sag
'sink' is the definition.
(sagging is a kind of sinking)
'fuel to rise' is the wordplay.
'fuel' becomes 'gas' (gas is a kind of fuel).
'to rise' says the letters should be written in reverse.
'gas' written backwards gives 'SAG'.
'and' is the link.
(Other definitions for sag that I've seen before include "Give way under pressure" , "Droop, flag" , "Sinking" , "Drop" , "Give in the middle" .)