Bird and pig surrounded barrier (7)
I believe the answer is:
swallow
'bird' is the definition.
(swallow is a kind of bird)
'pig surrounded barrier' is the wordplay.
I cannot really understand how this works, but
'barrier' could be 'wall' (I've seen this before) and 'wall' is found within the answer.
'pig' could be 'sow' (I've seen this in another clue) and 'sow' is present in the remaining letters.
No letters remain.
This may be the basis of clue (or it may be nonsense).
'and' acts as a link.
Can you help me to learn more?
(Other definitions for swallow that I've seen before include "Accept" , "It's like a swift - gulp" , "Songbird" , "Fall for; bird" , "Believe gullibly - bird" .)