Soldier's old large umbrella (7)
I believe the answer is:
parasol
'umbrella' is the definition.
(I've seen this before)
'soldier's old large' is the wordplay.
'soldier's' becomes 'paras' (para is a kind of soldier**).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'large' becomes 'l'.
'paras'+'o'+'l'='PARASOL'
(Other definitions for parasol that I've seen before include "cover" , "Protection from sun" , "Sunshade" , "Desert Shield?" , "protection from the rays" .)