Quiet person getting on old-fashioned device (5)
I believe the answer is:
pager
'old-fashioned device' is the definition.
'pager' can be an answer for 'device' (I have seen 'Bleeping device' mean 'pager' so perhaps 'device' could also mean 'pager'). I am not certain of the 'old-fashioned' bit.
'quiet person getting' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'person' becomes 'ager' (I can't explain this - if you can you should give a lot more credence to this answer).
'getting' is a charade indicator (letters next to each other).
'p'+'ager'='PAGER'
'on' is the link.
Can you help me to learn more?
(Other definitions for pager that I've seen before include "Radio alert device" , "Bleeper device" , "Small radio bleeper for contact" , "Contact device" , "One calling" .)