Company doctor's card (4)
I believe the answer is:
comb
'card' is the definition.
(thesaurus)
'company doctor's' is the wordplay.
'company' becomes 'co' (abbreviation).
'doctor' becomes 'mb' (Bachelor of Medicine, Medicinae Baccalaureus**).
'co'+'mb'='COMB'
(Other definitions for comb that I've seen before include "Red crest on a cock's head" , "Something with teeth (for the hair!)" , "Search thoroughly or tidy hair" , "Search well; bird's crest" , "Toothed implement - search (the area)" .)