Labrador, say, starts to gobble grub outside peacekeepers’ party? (6)
I believe the answer is:
Here is my best explanation:
'labrador say' is the definition.
'starts to gobble grub outside peacekeepers' party?' is the subsidiary indication.
'starts to' indicates taking the first letters.
'outside' means one lot of letters goes inside another.
'peacekeepers' party?' becomes 'undo' (I can't explain this - if you can you should give a lot more credence to this answer).
The initial letters of 'gobble grub' is 'gg'.
'gg' placed around 'undo' is 'gundog'.
(Another definition for gundog that I've seen is "That could be a pointer".)