The most common and most likely answer to this crossword clue is the 6 letter word INFILL
I
N
F
I
L
L
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The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does INFILL mean?
INFILL noun- That which fills in a space, hole or gap.
- The redecoration of a fingernail or toenail after it has grown, to prevent an unsightly gap.
- To fill in a space, hole or gap.
- To rededicate land in an urban environment to new construction.
- Infiltration, the act of going into a place.