Hello x_word_fan,
I enjoyed this EV, despite the setter being "Mr O". I am sure I heard Devadolly's cry of despair as she read who had set this EV! To be honest though, this was at the easier end of his previous offerings.
As far as 27d is concerned, replace the excluded letter between the 1st and 2nd of the grid entry, then consult the BRB for the first 4 letters. Letters 5 and 6 of the whole word are commonly used abbreviations for the last 2 words of the clue. In my BRB, 9th edition, the complete word is in brackets 2 entries further down the page than the entry for the first 4 letters.
Soon be time to pour a Glenlivet to help prepare dinner!