Famous old market in bay — ten grand for refurbishment (6,6)
I believe the answer is:
covent garden
'famous old market' is the definition.
(historical site of a London market)
'bay ten grand for refurbishment' is the wordplay.
'bay' becomes 'cove' (I've seen this before).
'for refurbishment' indicates anagramming the letters.
'ten'+'grand'='tengrand'
'tengrand' is an anagram of 'ntgarden'.
'cove'+'ntgarden'='COVENT GARDEN'
'in' acts as a link.
(Other definitions for covent garden that I've seen before include "Royal Opera House location" , "London's old fruit and veg market" , "Site of London's Royal Opera House" , "London tourist area with opera house" .)