First male worker is resolute (7)
I believe the answer is:
adamant
'resolute' is the definition.
(both can mean determined)
'first male worker' is the wordplay.
'first male' becomes 'adam'.
'worker' becomes 'ant' (worker is a type of ant).
'adam'+'ant'='ADAMANT'
'is' is the link.
(Other definitions for adamant that I've seen before include "Hard stone" , "Insistent, inflexible" , "6a [PRINCESS IDA] 's fortress < for unyielding" , "Definite and unyielding" , "Determined and unyielding to requests" .)