Is unwilling to take any further action! (8)
I believe the answer is:
retreats
'is' is the definition.
Although both the answer and definition are verbs in their -s form, I don't understand how one could define the other.
'unwilling to take any further action' is the wordplay.
I cannot really see how this works, but
'take' could be 'eat' (eating is a kind of taking) and 'eat' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for retreats that I've seen before include "tactical withdrawals" , "Backs away" , "Of army, falls back before enemy attack" , "Places that afford peace and quiet" , "Recedes" .)