They don't worry the steeple jack - he has bad sight (7)
I believe the answer is:
heights
'they don't worry the steeple jack he has bad sight' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'he has bad sight' is the wordplay.
'has' says to put letters next to each other.
'bad' indicates anagramming the letters.
'sight' is an anagram of 'ights'.
'he'+'ights'='HEIGHTS'
Can you help me to learn more?
(Other definitions for heights that I've seen before include "High places" , "Peaks" , "See 23 ac" , "Distances from top to bottom" , "Summits" .)