Slips perhaps in heather by North American lake (8)
I believe the answer is:
lingerie
'slips perhaps' is the definition.
(slip is a type of lingerie)
'heather by north american lake' is the wordplay.
'heather' becomes 'ling' (synonyms).
'by' means one lot of letters go next to another.
'north american lake' becomes 'erie' (I've seen this in another clue).
'ling'+'erie'='LINGERIE'
'in' acts as a link.
(Other definitions for lingerie that I've seen before include "Fancy underwear for women" , "CLOTHING" , "Women's underwear and nightclothes" , "Women's flimsy underwear" , "Scanties" .)