Dream of cleric on lake (7)
I believe the answer is:
reverie
'dream' is the definition.
(reverie is a kind of dream)
'cleric on lake' is the wordplay.
'cleric' becomes 'rev' (abbreviation for Reverend).
'on' means one lot of letters go next to another.
'lake' becomes 'erie' (Lake Erie is one of the Canadian/US 'Great Lakes').
'rev'+'erie'='REVERIE'
'of' is the link.
(Other definitions for reverie that I've seen before include "A dreamlike state, daydream" , "Daydream, meditation" , "Aimless train of thought" , "A waking dream" , "A day dream; a word used in the first ever 2 dn" .)