Gulf hosts to condemn outdated fossil fuel use? (3,4)
I believe the answer is:
gas lamp
'condemn outdated fossil fuel use?' is the definition.
I can't tell whether this defines the answer.
'gulf hosts to' is the wordplay.
'gulf' becomes 'gap' (I've seen this in another clue).
'hosts' is an insertion indicator (inserted letters are welcomed or hosted).
'to' becomes 'slam' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'gap' placed around 'slam' is 'GAS-LAMP'.
Can you help me to learn more?
(Other definitions for gas lamp that I've seen before include "Burning source of light" , "Sort of light" , "Form of illumination" , "lighter" , "Victorian street light" .)