One sober person in view to avoid action (3,5)
I believe the answer is:
sit tight
'avoid action' is the definition.
(to sit tight is to do nothing)
'one sober person in view' is the wordplay.
'one' becomes 'i' (Roman numeral).
'sober person' becomes 'TT' (short for teetotal).
'in' means one lot of letters goes inside another.
'view' becomes 'sight' (synonyms).
'i'+'tt'='itt'
'itt' placed inside 'sight' is 'SIT TIGHT'.
'to' acts as a link.
(Other definitions for sit tight that I've seen before include "Informally, remain sedentary, don't act" , "Maintain one's seat" , "Be too drunk to stand?" , "Keep one's position" , "Don't move" .)