Gander and dog heard (4)
I believe the answer is:
peek
'gander' is the definition.
(I've seen this in another clue)
'dog heard' is the wordplay.
'dog' becomes 'peke' (short for Pekingese).
'heard' shows a homophone (sound like).
'peke' sounds like 'PEEK'.
'and' is the link.
(Other definitions for peek that I've seen before include "Quick or furtive look" , "Repeatedly look like this" , "Glimpse" , "Quick, sly look" , "Furtive glance" .)