Private place to drink Erdinger on vacation (5)
I believe the answer is:
inner
'private' is the definition.
(as in one's private or inner thoughts)
'place to drink erdinger on vacation' is the wordplay.
'place to drink' becomes 'inn' (type of drinking establishment).
'on vacation' means to remove the middle letters (after the inside letters have vacated the word).
'erdinger' with its middle removed is 'er'.
'inn'+'er'='INNER'
(Other definitions for inner that I've seen before include "Hidden" , "More secret, private" , "just missing the gold" , "Opposite of 13" , "Essential - most private" .)