Some patriots form musical group (4)
I believe the answer is:
trio
'musical group' is the definition.
(trio is a kind of musical group)
'some patriots form' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'TRIO' can be found hidden inside 'patriots form'.
(Other definitions for trio that I've seen before include "wise men?" , "Group of Magi?" , "Threesome" , "father, spirit and son" , "Chamber group" .)