Not under the influence of various Boers (5)
I believe the answer is:
sober
'not under the influence' is the definition.
(I've seen this in another clue)
'various boers' is the wordplay.
'various' indicates anagramming the letters.
'boers' anagrammed gives 'SOBER'.
'of' acts as a link.
(Other definitions for sober that I've seen before include "Dignified and sombre in manner: dry" , "Serious or solemn and not drunk" , "In control of one's faculties" , "On the wagon" , "Far from drunk" .)