Leaders from Leyton Orient and Northampton Town worried regarding pitch (5)
I believe the answer is:
tonal
'regarding pitch' is the definition.
(I know this)
'leaders from leyton orient and northampton town worried' is the wordplay.
'leaders from' indicates taking the first letters.
'worried' is an anagram indicator (worry can mean to interfere with or disturb).
The initial letters of 'leyton orient and northampton town' is 'loant'.
'loant' with letters rearranged gives 'TONAL'.
(Other definitions for tonal that I've seen before include "Using conventional keys/harmonies" , "of sound quality" , "Like music that uses keys" , "With conventional key and harmony" , "It's wood can be used to make twenty three dn" .)