That little crossword clue 'Scottish cap' always makes me pause a beat — it's one of those short, satisfying fills. In most British-style grids the go-to fill is TAM, three letters, tidy and common. If the enumeration in the puzzle is longer you might see TAM O'SHANTER written out fully (often without punctuation in crosswords), which is the traditional name of the bonnet that inspired the poem 'Tam O'Shanter'.
I usually scan crossings first: if the pattern is A and the clue is simply Scottish headwear, TAM fits like a glove. If the grid wants something longer, think of GLENGARRY (a type of Scottish cap), BONNET, or TAM-O-SHANTER spelled out. Crossword setters love TAM because it’s compact and culturally specific, so it often turns up in quick puzzles. For me, spotting the length and checking intersecting letters is the fastest route to the right fill, and I always smile when a tiny TAM unlocks a chunk of the puzzle.