Muscle (6)
'muscle' is the definition.
(biceps is a kind of muscle)
This is all the clue.
(Other definitions for biceps that I've seen before include "Arm workers" , "Muscles on upper arms" , "Contractor" , "Forearm-flexing muscle" , "Elbow-bending muscle" .)
'muscle' is the definition.
(triceps is a kind of muscle)
This is the entire clue.
(Other definitions for triceps that I've seen before include "army feature?" , "Green citrus fruit" , "Muscle at the back of the upper arm" , "Muscle that extends the forearm" , "Upper-arm muscle" .)
'muscle' is the definition.
(synonyms)
This is all the clue.
(Other definitions for brawn that I've seen before include "This is strong" , "Jellied meat -- not brain!" , "perhaps, a sandwich filling" , "Physical strength; cooked meat" , "Muscularity" .)