Hold light to cover left side primarily (6)
I believe the answer is:
nelson
'hold' is the definition.
(wrestling hold)
'light to cover left side primarily' is the wordplay.
'light' becomes 'neon' ().
'to cover' means one lot of letters goes inside another.
'primarily' suggests taking the first letters.
The first letters of 'left side' is 'ls'.
'neon' enclosing 'ls' is 'NELSON'.
(Other definitions for nelson that I've seen before include "Lancashire town" , "Naval hero who died at Trafalgar" , "Maritime chief" , "Horatio ..., British admiral" , "Sailor" .)