First man and worker resolute (7)
I believe the answer is:
adamant
'resolute' is the definition.
(both can mean determined)
'first man and worker' is the wordplay.
'first' becomes 'a'.
'man' becomes 'dam' (I can't justify this - if you can you should give a lot more credence to this answer).
'and' is a charade indicator (letters next to each other).
'worker' becomes 'ant' (worker is a type of ant).
'a'+'dam'+'ant'='ADAMANT'
Can you help me to learn more?
(Other definitions for adamant that I've seen before include "intractable" , "Inexorable" , "Refusing to change opinion" , "Unshakable (in an opinion)" , "Refusing to budge" .)