No good cycling on island, not much cover (6)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

“g”(abbrev. for “good”) deleted from ( No … ) “biking”(cycling/riding a bike) placed above ( on , in a down clue) I(abbrev. for “island”). Defn: A two-piece swimming costume with …. Named after the island in the Bikini Atoll, where nuclear bombs were once tested.