Fat use modifying tango (4)
I believe the answer is:
suet
'fat' is the definition.
(I know that suet is a type of edible fat)
'use modifying tango' is the wordplay.
'modifying' is an anagram indicator (I've seen 'modified' mean this).
'tango' becomes 'T' (phonetic alphabet: alpha, bravo, charlie etc.).
'use' with letters rearranged gives 'sue'.
'sue'+'t'='SUET'
(Other definitions for suet that I've seen before include "Hard white cooking fat" , "Hard edible fat" , "Hard fat in cattle and sheep" , "Edible fat used in cooking" , "Solid fat used in cooking" .)