Tourists' vacation spent, in essence, mapmaking waterside (13)
I believe the answer is:
holidaymakers
'tourists'' is the definition.
('holidaymaker' can be a synonym of 'tourist')
'vacation spent in essence mapmaking waterside' is the wordplay.
I cannot quite see how this works, but
'vacation' could be 'holiday' (synonyms) and 'holiday' is present in the answer.
The remaining letters 'makers' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for holidaymakers that I've seen is " Tourists".)