Put a match to high explosive - moving with alacrity! (5)
I believe the answer is:
lithe
'moving with alacrity' is the definition.
I can't tell whether this defines the answer.
'put a match to high explosive' is the wordplay.
'put a match to' becomes 'lit' (I've seen this in another clue).
'high explosive' becomes 'he'.
'lit'+'he'='LITHE'
Can you help me to learn more?
(Other definitions for lithe that I've seen before include "Loose-limbed" , "Able to move and bend gracefully" , "showing great athletic ability" , "Lissome, supple" , "Physically flexible or supple" .)