Youth leaders in Leeds and Doncaster (3)
I believe the answer is:
lad
'youth' is the definition.
(lad means a young man)
'leaders in leeds and doncaster' is the wordplay.
'leaders in' suggests taking the first letters.
The first letters of 'leeds and doncaster' is 'LAD'.
(Other definitions for lad that I've seen before include "Son" , "(Housman's Shropshire) boy" , "A young chap into ballads" , "Youngster" , "Scottish lover" .)