Seize butterfly perched on new grass coming up (10)
I believe the answer is:
commandeer
'seize' is the definition.
(commandeering is a kind of seizing)
'butterfly perched on new grass coming up' is the wordplay.
I cannot really see how this works, but
'butterfly' could be 'comma' (comma butterfly is a kind of butterfly) and 'comma' is found in the answer.
'new' could be 'n' (common abbreviation eg NT for New Testament) and 'n' is found within the answer.
The remaining letters 'deer' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for commandeer that I've seen before include "Take by force" , "requisition" , "Appropriate" , "Confiscate" , "Take control of for military purposes" .)