Looking for water? Get a boat, then give us a sea shanty, perhaps ... (7)

'looking for water?' is the definition.
(dowsing can supposedly locate water)

'a boat then give us a sea shanty perhaps' is the wordplay.
'a boat' becomes 'dow' (dhow or dow is a type of boat).
'then' means one lot of letters go next to another.
'give us a sea shanty perhaps' becomes 'sing' (a sea shanty is a song).
'dow'+'sing'='DOWSING'

'get' acts as a link.