One doing casual work on a lock can be enticing (9)
I believe the answer is:
temptress
'one doing casual work' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'lock can be enticing' is the wordplay.
I cannot quite understand how this works, but
'lock' could be 'ress' (I've seen this in another clue) and 'ress' is found in the answer.
The remaining letters 'tempt' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'on a' is the link.
Can you help me to learn more?
(Other definitions for temptress that I've seen before include "Enticing female" , "Siren, say" , "charmer" , "Alluring woman" , "seductive type" .)