Thespian has keys to lock (7)
I believe the answer is:
actress
'thespian' is the definition.
(actress is a kind of thespian)
'keys to lock' is the wordplay.
'keys to' becomes 'ac' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'lock' becomes 'tress' (both can mean a piece of hair).
'ac'+'tress'='ACTRESS'
'has' is the link.
Can you help me to learn more?
(Other definitions for actress that I've seen before include "eg Emma Thompson" , "Female thespian" , "dame on stage?" , "Garland perhaps" , "Stage performer" .)