The efficiency will depend on the SQL - specifically, how much you are SELECTing. Since you only use the statement to produce an array of account numbers, you should only select that column.

What is $TOALLCLAIM? It looks like a different name for $TOALL, which should be lexical, or else omitted entirely.

Assuming 'ACCOUNT#' is a legal column name in your db, and that your DBD supports the method, the whole thing might be written,

my @array_claim = map {
    cleaner($_)
} @{$dbh->selectcol_arrayref( 'select ACCOUNT# from datable')};
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You'll need something a little more elaborate to quote data to be entered in a where clause.