18a. It can be hard to negotiate with head - how one may turn cheek?
TURTLENECK
25a. It'll be fine if the volume's not turned up, and is like this
UNRENEWED
6d. Mushroom offered by a South London club
AGARIC
20a. Container used by American is terracotta
CANISTER
17d. Insolent in attitude, going up to trade centre
ENTREPOT
Parses for the above please.