Company chairman's last kind companion (7)
I believe the answer is:
consort
'companion' is the definition.
(I've seen this before)
'company chairman's last kind' is the wordplay.
'company' becomes 'co' (abbreviation).
'last' suggests the final letters.
'kind' becomes 'sort' (synonyms).
The last 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?" .)