Socialist's troops eating small pieces variously seen in this grid (8)
I believe the answer is:
chessmen
'pieces variously seen in this grid' is the definition.
Although both the answer and 'grid' are nouns, they are not in the same form of the noun.
'socialist's troops eating small' is the wordplay.
'socialist's' becomes 'Che's' (revolutionary Che Guevara).
'troops' becomes 'men' (men can mean soldiers).
'eating' is an insertion indicator.
'small' becomes 's' (abbreviation - e.g. clothes size).
'ches'+'men'='chesmen'
'chesmen' going around 's' is 'CHESSMEN'.
(Other definitions for chessmen that I've seen before include "Board pieces" , "Knights, rooks, pawns etc collectively - even the queen" , "'Bishops, pawns etc (8)'" , "Pawns, queens, rooks etc" , "Knights, bishops, rooks etc" .)