Little dog heard showing resentment (5)
I believe the answer is:
pique
'resentment' is the definition.
(I've seen this before)
'little dog heard' is the wordplay.
'little dog' becomes 'peke' (I've seen this in another clue).
'heard' indicates a 'sounds like' (homophone) clue.
'peke' sounds like 'PIQUE'.
'showing' acts as a link.
(Other definitions for pique that I've seen before include "Bad temper" , "Umbrage; irritation" , "Hurt feelings" , "Show of annoyance" , "Stimulate (someone's interest)" .)