Ring modulator usually features (5)
I believe the answer is:
torus
'ring' is the definition.
(I've seen this before)
'modulator usually features' is the wordplay.
'features' says the answer is hidden in the clue (I've seen 'featuring' mean this).
'TORUS' can be found hidden inside 'modulator usually'.
(Other definitions for torus that I've seen before include "Doughnut-shaped solid" , "Ring shape" , "Ring shaped like doughnut with hole" , "Shape of doughnut" , "Doughnut-shaped figure" .)