Soldier scowls occasionally, shading head with this? (7)
I believe the answer is:
parasol
'shading head with this?' is the definition.
'soldier scowls occasionally' is the wordplay.
'soldier' becomes 'para' (para is a kind of soldier).
'occasionally' indicates alternate letters.
The alternating letters of 'scowls' are 'sol'.
'para'+'sol'='PARASOL'
(Other definitions for parasol that I've seen before include "Light umbrella giving shade from sun" , "It's put up to provide shade" , "protection from the rays" , "for protection from the elements" , "Fair-weather umbrella" .)