Delap's last long throw (5)
I believe the answer is:
pitch
'throw' is the definition.
(pitch is a kind of throw)
'delap's last long' is the wordplay.
'last' suggests the final letters.
'long' becomes 'itch' (to long or itch for something is to desire it).
The last letter of 'delap' is 'p'.
'p'+'itch'='PITCH'
(Other definitions for pitch that I've seen before include "Slope, of a roof say" , "cast?" , "Throw - black stuff" , "Throw; tar" , "Football ground" .)