Tense individual drinking on vacation close to collapse (2,4)
I believe the answer is:
on edge
'tense' is the definition.
(on edge can mean tense or stressed)
'individual drinking on vacation close to collapse' is the wordplay.
'individual' becomes 'one' (an individual is one person).
'on vacation' suggests removing the centre.
'close to' says to take the final letters (the close/ending of).
'drinking' with its middle removed is 'dg'.
The final letter of 'collapse' is 'e'.
'one'+'dg'+'e'='ON EDGE'
(Other definitions for on edge that I've seen before include "Cliff-top walker may be" , "Nervous and tense - close to cliff?" , "Anxious, nervy" , "Under stress" , "'Tense, nervous (2,4)'" .)