Wordplay as given
Insect: abbreviation for adult, synonym for was, another's head. A clever clue because 'nipping' can refer to the wordplay or the definition.
Kirkcaldy: Scottish words for objective and slate (not the stone sort), usual abbreviation.
As for the adjustments: I guess they were all anagrams, although the Scotsman clue was maybe a pointer for the endgame.