Bought a supply of, to be used as nests (4,2)

'bought' is the definition.
The answer and definition can be both to do with ownership as well as being past participle verbs.
Perhaps they are linked in a way I don't understand?

'a supply of to be used as nests' is the wordplay.
I cannot really understand how this works, but
'a' is within the answer.
'as' could be 'in' (I've seen this in other clues) and 'in' is found within the answer.
The remaining letters 'lid' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?