Attendant with right signalling device (5)
I believe the answer is:
pager
'device' is the definition.
(I have seen 'Bleeping device' mean 'pager' so perhaps 'device' could also mean 'pager')
'attendant with right' is the wordplay.
'attendant' becomes 'page' (page is a kind of attendant).
'with' means one lot of letters go next to another.
'right' becomes 'r' (common abbreviation).
'page'+'r'='PAGER'
'signalling' acts as a link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for pager that I've seen before include "This may summon one" , "Electronic messaging device" , "It alerts those on call" , "Old electronic bleeping device" , "One calling" .)