On vacation, relative and I get horribly run down (9)
I believe the answer is:
denigrate
'run down' is the definition.
(I've seen this before)
'on vacation relative and i get horribly' is the wordplay.
'on vacation' says to hollow out the word (remove centre letters).
'horribly' indicates an anagram.
'relative' with its centre removed is 're'.
're'+'and'+'i'+'get'='reandiget'
'reandiget' with letters rearranged gives 'DENIGRATE'.
(Other definitions for denigrate that I've seen before include "Defame" , "Bad-mouth" , "Run down" , "Disparage" , "Slight" .)