Take small bird (5)
I believe the answer is:
steal
'take' is the definition.
(stealing is a kind of taking)
'small bird' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'bird' becomes 'teal' (type of duck).
's'+'teal'='STEAL'
(Other definitions for steal that I've seen before include "Pilfer" , "Take without permission" , "a snip!" , "Rob" , "Take illegally" .)