Agile male struck first (5)
I believe the answer is:
lithe
'agile' is the definition.
(I've seen this before)
'male struck first' is the wordplay.
'male' becomes 'he' (he refers to a man).
'struck' becomes 'lit' (I can't justify this - if you can you should believe this answer much more).
'first' says to put letters next to each other.
'he' after 'lit' is 'LITHE'.
Can you help me to learn more?
(Other definitions for lithe that I've seen before include "Slim and supple" , "Supple and limber" , "Svelte" , "Physically supple, agile" , "Physically flexible or supple" .)