Soldier returned - no use performing some rock (7)
I believe the answer is:
igneous
'some rock' is the definition.
(igneous rock is a kind of rock)
'soldier returned no use performing' is the wordplay.
'soldier' becomes 'GI' (term for US soldier).
'returned' says the letters should be written backwards.
'performing' indicates anagramming the letters (the letters move around or 'perform').
'gi' reversed gives 'ig'.
'no'+'use'='nouse'
'nouse' is an anagram of 'neous'.
'ig'+'neous'='IGNEOUS'
(Other definitions for igneous that I've seen before include "(Of rock) solidified from a molten state" , "Like fire - type of rock" , "(Of rock) solidified from lava or magma" , "Of fire, like rocks formed from molten material" , "Formed by intense heat" .)