Some rascal on glock in accompaniment (5)
I believe the answer is:
along
'in accompaniment' is the definition.
(synonyms)
'some rascal on glock' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'ALONG' is hidden in the letters of 'rascal on glock'.
(Other definitions for along that I've seen before include "Beside - as groups often sing!" , "From one end to the other" , "With a forward motion: in accompaniment" , "Sea monster, opposite Charybdis" , "Throughout; onward" .)