Training lieutenant to sprint (4)
I believe the answer is:
pelt
'to sprint' is the definition.
(both can mean to run fast)
'training lieutenant' is the wordplay.
'training' becomes 'PE' (Physical Education).
'lieutenant' becomes 'lt' (abbreviation for lieutenant).
'pe'+'lt'='PELT'
(Other definitions for pelt that I've seen before include "Skin - throw things at" , "Run fast - hide - pepper" , "Pour; hide" , "Animal hide" , "Hide; rain" .)