Use live explosive that's had to pin down (7)
I believe the answer is:
elusive
'had to pin down' is the definition.
I can't judge whether this definition defines the answer.
'use live explosive' is the wordplay.
'explosive' indicates anagramming the letters.
'use'+'live'='uselive'
'uselive' anagrammed gives 'ELUSIVE'.
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for elusive that I've seen before include "Slippery, hard to catch" , "Transient" , "Evil use (anag.)" , "Hard to pin down, slippery" , "Use veil to be difficult to catch" .)