Thanks to Tramp.
Found this on the gentle side, some parsings were difficult but the solutions not so hard to guess.
FOI 1d.
LOI 18, which I'd guessed early on but had trouble parsing and needed Google to confirm the answer.
COD 8, being a geek. Also liked 7, 10 and 19...happened to have the GK for 19.
Brendan, 22d parses as 3 (an acronym) inside 2. The definition in 27 is the final word of the clue.