Seven identical two-by-two squares in the completed grid must be highlighted to depict the unclued entries, each of two words.
 

Across

 
1    Eyesores left out of designs (5)
11    Beards or bristles I rate as ugly (7)
17    Was host dropping soprano, with tenor being groomed? (7)
18    Rust producer engineer replies to about oxygen (10)
19    State when they are drowned (4)
20    Said tool is a calculator (4)
25    Afternoon in sun melted plastic (5)
26    In debates, he backed monarchy (5)
27    Former US colony in league with peninsula (7)
31    Ace of spades to give information about...