The {7} cells
The {8} cells {1} are an Almost Locked Set (ALS) that is linked to the bivalue cell {2} through the value {4}, so if the value {3} was eliminated from all {7} Wing cells then the remaining value {3} of {2} leaves just {9} values to fill the {8} ALS cells, which is invalid; so {4} is "locked into" these {7} Wing cells, hence {3} can be removed from cells which see all {3}'s in the Wing.
Therefore