Pocketed by OAP, age-related communications 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')
'pocketed by oap age-related communications' is the wordplay.
'PAGER' is hidden in amongst the letters.
However, I'm unsure how the hidden word is indicated.
Can you help me to learn more?
(Other definitions for pager that I've seen before include "It alerts those on call" , "Old electronic bleeping device" , "One calling" , "message on this?" , "Small radio bleeper for contact" .)