Dog leapt to have a look (4)
I believe the answer is:
ogle
'a look' is the definition.
(I know that ogle is a more specific form of the action look)
'dog leapt to have' is the wordplay.
'to have' indicates the answer is hidden within the clue.
'OGLE' is hidden in the letters of 'dog leapt'.
(Other definitions for ogle that I've seen before include "Look at inappropriately" , "Stare at in a lecherous manner" , "John -, diarist, - Waugh, novelist" , "Cast amorous glances" , "Perv" .)