Judge in predicament before boarding plane (9)
I believe the answer is:
preflight
'before boarding plane' is the definition.
(before a flight begins)
'judge in predicament' is the wordplay.
'judge' becomes 'ref' (referee).
'in' means one lot of letters goes inside another.
'predicament' becomes 'plight' (synonyms).
'ref' placed inside 'plight' is 'PREFLIGHT'.
(Other definitions for preflight that I've seen before include "Before take-off" , "before anything takes off" , "before setting off on journey" .)