Climb endlessly on a ladder-like structure (5)
I believe the answer is:
scala
'ladder-like structure' is the definition.
I know nothing about this answer so I can't tell whether this works.
'climb endlessly on a' is the wordplay.
'climb' becomes 'scale' (scaling is a kind of climbing).
'endlessly' means to remove the last letter.
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'scale' with its last letter taken off is 'scal'.
'scal'+'a'='SCALA'
Can you help me to learn more?
(Other definitions for scala that I've seen before include "La . . . . . is a famous Opera House in Milan" , "La --, Milan theatre" .)