26d Directly towards the Arctic. (3,5) ?U?/NORTH
39d Second-rate tennis stroke-maker gets support. (7) ?R?C???
45d Agent Works endlessly. (6) ?A?T?R
51de Pool or Lake. (4) ???E Is it 'mere'?
53a Oily resin from tropical trees used in varnishes and resin. ????I