Late at night I'm stuck on quite a few, but answers to the following across clues should help me to complete:
13a It's backed in hard-bitten academy? No longer (4) ?A?E
18a Harmonise with feature in kitchen so to speak (4) S?O?
20a Diverting manoeuvres and intrigues (7,5) ?U?N?N?/A???E
24a Critic on the Spectator? (8) R???E???