Fake warning about measure of gravitation (5)
I believe the answer is:
forge
'fake' is the definition.
(forge can mean to fake or counterfeit)
'warning about measure of gravitation' is the wordplay.
'warning' becomes 'fore' (shouted in golf).
'about' indicates putting letters inside.
'measure of gravitation' becomes 'g' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'fore' enclosing 'g' is 'FORGE'.
Can you help me to learn more?
(Other definitions for forge that I've seen before include "Fabricate" , "Furnace for heating metal" , "Smith's workplace" , "Create; counterfeit" , "Form by heating and hammering" .)