Book launch takes stamina (5)
I believe the answer is:
fibre
'book launch takes stamina' is the definition.
I can't tell whether this definition defines the answer.
'book launch takes stamina' is the wordplay.
'launch' says to take the initial letters (the letter which launches the word).
'takes' means one lot of letters goes inside another (take can mean to capture or invade).
'stamina' becomes 'fire' (I can't explain this - if you can you should give a lot more credence to this answer).
The first letter of 'book' is 'b'.
'b' inserted inside 'fire' is 'FIBRE'.
Can you help me to learn more?
(Other definitions for fibre that I've seen before include "Thread; stamina" , "Thread - strength of character" , "Textile thread; roughage" , "Threadlike substance" , "Thread, filament" .)