Dog left 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 look)
'dog left to have' is the wordplay.
'to have' says the answer is hidden in the clue.
'OGLE' is hidden within 'dog left'.
(Other definitions for ogle that I've seen before include "Amorous glance" , "Regard lecherously" , "Make eyes at" , "Gaze at lecherously" , "Gawp" .)