Company chairman's last kind companion (7)
I believe the answer is:
consort
'companion' is the definition.
(I know that companion is a more specific form of the action consort)
'company chairman's last kind' is the wordplay.
'company' becomes 'co' (abbreviation).
'last' suggests the final letters.
'kind' becomes 'sort' (synonyms).
The final letter of 'chairman' is 'n'.
'co'+'n'+'sort'='CONSORT'
(Other definitions for consort that I've seen before include "helpmate" , "Group playing music" , "Small group; spouse" , "Hang out with" , "Prince Albert?" .)