Popular dog to bring on (5)
I believe the answer is:
incur
'bring on' is the definition.
(I've seen this before)
'popular dog' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'dog' becomes 'cur' (cur is a kind of dog).
'in'+'cur'='INCUR'
'to' acts as a link.
(Other definitions for incur that I've seen before include "Take on (obligation)" , "Bring on oneself, probably unpleasant" , "Become liable to (costs)" , "Arouse" , "Fall liable to" .)