Conclusion: pig, frog and bulldog all do it (6)
I believe the answer is:
ending
'conclusion' is the definition.
(I know that conclusion can be written as ending)
'pig frog and bulldog all do it' is the wordplay.
I cannot really understand how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is present in the answer.
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is located in the answer.
The remaining letters 'ding' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ending that I've seen before include "Putting a stop to" , "Closure" , "Climax" , "Finish" , "Closing down" .)