Hound dropping catch on vacation (5)
I believe the answer is:
pooch
'hound' is the definition.
(I've seen this in another clue)
'dropping catch on vacation' is the wordplay.
'dropping' becomes 'poo' (informal term for excrement).
'on vacation' says to hollow out the word (remove centre letters).
'catch' with its middle taken out is 'ch'.
'poo'+'ch'='POOCH'
(Other definitions for pooch that I've seen before include "Doggy" , "one of our best friends" , "Dog (colloq.)" .)