Birds left in traps (7)
I believe the answer is:
linnets
'birds' is the definition.
(linnet is a kind of bird)
'left in traps' is the wordplay.
'left' becomes 'l' (common abbreviation).
'traps' becomes 'nets' (net is a kind of trap).
'l'+'in'+'nets'='LINNETS'
(Other definitions for linnets that I've seen before include "birds" , "Common finches" , "wingers" , "Would they tweet" .)