Volcanic outflow (4)
'volcanic outflow' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lava that I've seen before include "Volcanic stream" , "What volcano ejects" , "Immature insect form" , "Volcanic emission" , "Flowing volcanic matter" .)
'volcanic outflow' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for magma that I've seen before include "hot stuff" , "crust's content" , "Molten or pasty rock" , "Lava" , "Glassy volcanic rock" .)