Precursor of some peripheral devices (6)
I believe the answer is:
herald
'precursor' is the definition.
('herald' can be a synonym of 'precursor')
'some peripheral devices' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'HERALD' is hidden in the letters of 'peripheral devices'.
'of' is the link.
(Other definitions for herald that I've seen before include "Usher in; proclaim" , "One making proclamations - harbinger" , "College of Arms official" , "Bringer of news" , "Foreshadow" .)