Golf between two old ladies is fiery stuff (5)
I believe the answer is:
magma
'fiery stuff' is the definition.
'magma' can be an answer for 'stuff' (magma is a kind of stuff). I am not sure about the 'fiery' bit.
'golf between two old ladies' is the wordplay.
'two old ladies' means two replacements for 'old lady'.
'golf' becomes 'g' (phonetic alphabet: alpha, bravo, charlie etc.).
'between' is an insertion indicator.
'old lady' becomes 'ma' (both can informally mean mother).
'old lady' becomes 'ma' (both can informally mean mother).
'ma'+'ma'='mama'
'g' put within 'mama' is 'MAGMA'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for magma that I've seen before include "Glassy volcanic rock" , "Hot material" , "Molten rock in the earth's crust" , "hot stuff" , "That's hot!" .)