Bags of empty tweets (10)
I believe the answer is:
drainpipes
'bags' is the definition.
(type of trousers - 'bags' can mean loose trousers)
'empty tweets' is the wordplay.
'empty' becomes 'drain' (draining is a kind of emptying).
'tweets' becomes 'pipes' (both can mean birdsong).
'drain'+'pipes'='DRAINPIPES'
'of' is the link.
(Other definitions for drainpipes that I've seen before include "Trousers with very narrow legs" , "used by cat burglars, perhaps?" .)