Family doctor at work's most important member of the team (7)
I believe the answer is:
kingpin
'important member of the team' is the definition.
I can't judge whether this definition defines the answer.
'family doctor at work's most' is the wordplay.
'family' becomes 'kin' (synonyms).
'doctor' becomes 'GP' (general practitioner).
'at work's' becomes 'in's' (eg in the office).
'most' means to remove the last letter.
'ins' with its last letter taken away is 'in'.
'kin'+'gp'+'in'='KINGPIN'
Can you help me to learn more?
(Other definitions for kingpin that I've seen before include "Essential person in organisation" , "Pink gin for indispensable person" , "Main bolt" , "Group leader" , "Most important member of organisation" .)