A caretaker's generic sort supporting company (9)
I believe the answer is:
concierge
'a caretaker's' is the definition.
(concierge is a kind of caretaker)
'generic sort supporting company' is the wordplay.
'sort' is an anagram indicator.
'supporting' is a charade indicator (letters next to each other) (in a down clue, some letters go below others).
'company' becomes 'co' (abbreviation).
'generic' with letters rearranged gives 'ncierge'.
'ncierge' after 'co' is 'CONCIERGE'.
(Other definitions for concierge that I've seen before include "One books tickets etc for hotel guests" , "Hall porter" , "hotel employee" , "Doorkeeper of hotel or apartment building" , "Residential block porter" .)