Reportedly, foreign water perhaps does well! (2,4)
I believe the answer is:
oh dear
'well' is the definition.
(both can mean exclamations of surprise)
'reportedly foreign water perhaps' is the wordplay.
'reportedly' shows a homophone (sound like).
'foreign water' becomes 'eau' ('water' in French).
'perhaps' becomes 'dear' (I can't justify this - if you can you should give a lot more credence to this answer).
'eau' sounds like 'oh'.
'oh'+'dear'='OH DEAR!'
'does' is the link.
(Other definitions for oh dear that I've seen before include "Never mind!" , "alas" , "Cry of dismay" , "What a pity/shame/surprise!" , "I say" .)