Leader leaving school gives pointer (5)
I believe the answer is:
arrow
'pointer' is the definition.
(I know that pointer can be written as arrow)
'leader leaving school' is the wordplay.
'leader leaving' means to remove the first letter.
'school' becomes 'Harrow' (famous UK public school).
'harrow' with its first letter taken away is 'ARROW'.
'gives' acts as a link.
(Other definitions for arrow that I've seen before include "pointer to the way forward" , "Indicator; missile" , "It caught Harold's eye" , "One in a quiver" , "Arm" .)