Signals you might pick up for lots of people waiting (6)
I believe the answer is:
queues
'lots of people waiting' is the definition.
'signals you might pick up' is the wordplay.
'signals' becomes 'cues'.
'you might pick up' indicates a 'sounds like' (homophone) clue.
'cues' sounds like 'QUEUES'.
'for' is the link.
(Other definitions for queues that I've seen before include "Lines of waiting people or vehicles" , "Lines of waiters" , "Line of waiting people or vehicles" , "Waits in line" , "lots of waiters" .)