Performers have a key to locks (9)
I believe the answer is:
actresses
'performers' is the definition.
(actress is a kind of performer)
'a key to locks' is the wordplay.
'key to' becomes 'c' (I've seen this in other clues).
'locks' becomes 'tresses' (I've seen this in another clue).
'a'+'c'+'tresses'='ACTRESSES'
'have' acts as a link.
(Other definitions for actresses that I've seen before include "Female performers" , "Starlets" , "Female impersonators" , "Female thespians" , "Girls in play" .)