Trouble on vacation with the barking canines? (5)
I believe the answer is:
teeth
'canines?' is the definition.
(canine is a kind of tooth)
'trouble on vacation with the barking' is the wordplay.
'on vacation' means to remove the middle letters (after the inside letters have vacated the word).
'with' is a charade indicator (letters next to each other).
'barking' indicates an anagram (UK slang for mad).
'trouble' with its centre removed is 'te'.
'the' anagrammed gives 'eth'.
'te'+'eth'='TEETH'
(Other definitions for teeth that I've seen before include "Canines, molars, etc" , "Canines, maybe" , "Bony structures for eating" , "Eg, canines, incisors" , "Force v" .)