Lawn with pig troubled bird (7)
I believe the answer is:
lapwing
'bird' is the definition.
(lapwing is a kind of bird)
'lawn with pig troubled' is the wordplay.
'with' means one lot of letters go next to another.
'troubled' indicates anagramming the letters.
'lawn' put after 'pig' is 'piglawn'.
'piglawn' anagrammed gives 'LAPWING'.
(Other definitions for lapwing that I've seen before include "Flier" , "Bird of the plover family" , "Crested plover" , "wader" , "Variety of plover" .)