Dirty like certain lakes? (7)
I believe the answer is:
tarnish
'dirty like certain lakes?' is the definition.
'tarnish' can be an answer for 'dirty' (thesaurus). I am unsure of the 'like certain lakes?' bit.
'dirty like' is the wordplay.
'dirty' becomes 'tarn' (I can't explain this - if you can you should believe this answer much more).
'like' becomes 'ish' (similar in meaning).
'tarn'+'ish'='TARNISH'
(Other definitions for tarnish that I've seen before include "Lose shine" , "Mountain lake" , "Lose lustre; sully" , "(Of metal) lose lustre" , "Stain or blemish, perhaps a reputation" .)