Very damp, old township (6)
I believe the answer is:
soweto
'township' is the definition.
(township in Johannesburg in South Africa)
'very damp old' is the wordplay.
'very' becomes 'so' (both can mean 'extremely').
'damp' becomes 'wet' (similar in meaning).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'so'+'wet'+'o'='SOWETO'
(Other definitions for soweto that I've seen before include "part of South Africa" , "Scene of 1976 riots southwest of Johannesburg" , "Group of townships in South Africa" , "South African township area" , "place in Africa" .)