Noticed about ladder at regular points going up in sewers (7)
I believe the answer is:
needles
'sewers' is the definition.
(I've seen this before)
'noticed about ladder at regular points going up' is the wordplay.
'noticed' becomes 'seen' (I've seen this before**).
'about' is an insertion indicator.
'at regular points' indicates alternate letters.
'going up' says the letters should be written in reverse.
The alternating letters of 'ladder' are 'lde'.
'seen' enclosing 'lde' is 'seldeen'.
'seldeen' reversed gives 'NEEDLES'.
'in' is the link.
(Other definitions for needles that I've seen before include "They may play LPs" , "Conifer leaves" , "Pointers - goads" , "landmark" , "Teases or provokes with knitting implements" .)