On notice to adopt wild animals (6)
I believe the answer is:
aboard
'on' is the definition.
Both the definition and answer are adverbs. Maybe you can see an association between them that I don't see?
'notice to adopt wild animals' is the wordplay.
'notice' becomes 'ad' (short for advert).
'to adopt' means one lot of letters goes inside another.
'wild animals' becomes 'boar' (I can't explain this - if you can you should believe this answer much more).
'ad' enclosing 'boar' is 'ABOARD'.
Can you help me to learn more?
(Other definitions for aboard that I've seen before include "on a train, perhaps" , "On (eg, a ship)" , "on a liner, say" , "in a car" , "Part of the group" .)