Public relations hoo-ha in Madrid museum (5)
I believe the answer is:
prado
'madrid museum' is the definition.
(I've seen this before)
'public relations hoo-ha' is the wordplay.
'public relations' becomes 'pr'.
'hoo-ha' becomes 'ado' (I've seen this before).
'pr'+'ado'='PRADO'
'in' is the link.
(Other definitions for prado that I've seen before include "gallery for paintings" , "foreign gallery" , "picture-house" , "exhibits here?" , "Famous art gallery in Madrid" .)