The readable thirty-nine? (5)
I believe the answer is:
steps
'readable thirty-nine?' is the definition.
I can't judge whether this definition defines the answer.
'the' is the wordplay.
I cannot really understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
The remaining letters 'seps' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for steps that I've seen before include "See 23" , "Footfalls" , "Stairs; paces" , "taken to get on" , "Stages; ladder" .)