Picture capturing a swallow (3)
I believe the answer is:
eat
'swallow' is the definition.
(I've seen this in another clue)
'picture capturing a' is the wordplay.
'picture' becomes 'et' (I can't explain this - if you can you should believe this answer much more).
'capturing' is an insertion indicator.
'et' going around 'a' is 'EAT'.
Can you help me to learn more?
(Other definitions for eat that I've seen before include "tolerate in diet" , "Do cats - bats? Do bats - cats? (Alice in Wonderland)" , "Scoff" , "Be corrosive" , "Use a knife and fork" .)