Enjoyed that - very satisfying when i realised how to apply the first part of the message. can i just check, is the second part of the instruction re highlighting as straightforward as it seems?
Also few where parsing eludes me:
12a) oz's shooter for such wild cats - i know the correct letter, but not where it goes, or how shooter fits in.
25a) one may use non-latin form for moss, mixing word order up (know the correction here)
27a) cocky pike, chub-like fish leaves scorching (know correction here)
10d) The Beatles, say, not first to top position - i am not even certain of the unches here but cant see anything else that fits (and nor can chambers wordfinder)!