Old hat found in bar by a lake (5)
I believe the answer is:
banal
'old hat' is the definition.
'bar by a lake' is the wordplay.
'bar' becomes 'ban' (I've seen this before**).
'by' is a charade indicator (letters next to each other).
'lake' becomes 'l'.
'ban'+'a'+'l'='BANAL'
'found in' is the link.
(Other definitions for banal that I've seen before include "Uninspiring" , "Obvious and dull" , "Trite or fatuous" , "'Trite, time-worn (5)'" , "flat" .)