Delays providing material that won't hold prisoners (10)
I believe the answer is:
stonewalls
'delays providing material that won't hold prisoners' is the definition.
Although both the answer and definition are verbs in their -s form, I can't understand how one could define the other.
'delays providing material' is the wordplay.
I cannot really understand how this works, but
'material' could be 'stone' (stone is a kind of material) and 'stone' is present in the answer.
The remaining letters 'walls' 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?
(Other definitions for stonewalls that I've seen before include "Goes slow deliberately" , "Obstructs progress" .)