Revealed black labrador base (7)
I believe the answer is:
blabbed
'revealed' is the definition.
(blabbing is a kind of revealing)
'black labrador base' is the wordplay.
'black labrador' becomes 'blab' (I am not sure about this - if you are sure you should believe this answer much more).
'base' becomes 'bed' (both can mean the bottom of something).
'blab'+'bed'='BLABBED'
Can you help me to learn more?
(Other definitions for blabbed that I've seen before include "Let the cat out of the bag" , "Talked indiscreetly" , "Spilt the beans" .)