Flexible male struck first (5)
I believe the answer is:
lithe
'flexible' 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' put after 'lit' is 'LITHE'.
Can you help me to learn more?
(Other definitions for lithe that I've seen before include "Loose-limbed" , "Of body, flexible and supple" , "Svelte" , "showing great athletic ability" , "Slim and supple" .)