Exercise securing high salary freeze (8)
I believe the answer is:
paralyse
'freeze' is the definition.
(freeze can mean to paralyse or stop from moving)
'exercise securing high salary' is the wordplay.
'exercise' becomes 'pe' (Physical Education).
'securing' means one lot of letters goes inside another.
'high' is an anagram indicator (like drunk).
'salary' anagrammed gives 'aralys'.
'pe' going around 'aralys' is 'PARALYSE'.
(Other definitions for paralyse that I've seen before include "Make powerless, immobile, unable to function" , "make still" , "Immobilise a person" , "Bring to a standstill" , "Render immobile" .)