The first male worker is unyielding (7)
I believe the answer is:
adamant
'unyielding' is the definition.
(I've seen this in another clue)
'the first male worker' is the wordplay.
'the first male' becomes 'Adam' (first man in the Bible).
'worker' becomes 'ant' (worker is a type of ant).
'adam'+'ant'='ADAMANT'
'is' acts as a link.
(Other definitions for adamant that I've seen before include "Definite and unyielding" , "Legendary rock" , "Hard stone" , "unshakeable in purpose" , "uncompromising" .)