A quotation (in the Oxford Dictionary of Quotations) runs clockwise around the perimeter of the grid, beginning with the last letter of 20. The apostrophe has to be included where it appears. Five unclued lights are of a kind; one is directly linked to the quotation, the others indirectly.

Across

9 Dangerous atmosphere in outskirts of Hackney (5)

10    Criticise extremely burdensome tariff (6)

11    Careless ironworker losing wok by mistake (2,5)

13    Auntie putting end of thumb on buzzer (4)

15    Idiot and old spies regularly billed as ‘potentially connected’ (10)

16    Reportedly joined model, 33, in bath? (8)

20    Footballing great from Lazio once collared by detective...