Seal in lake perhaps? Verification to follow (10)
I believe the answer is:
waterproof
'seal' is the definition.
(I know that waterproof is a kind of seal)
'lake perhaps? verification to follow' is the wordplay.
'lake perhaps?' becomes 'water' (lake is a kind of water).
'verification' becomes 'proof' (I've seen this in another clue).
'to follow' means one lot of letters go next to another (some letters go after or follow others).
'water'+'proof'='WATERPROOF'
'in' acts as a link.
(Other definitions for waterproof that I've seen before include "Impermeable" , "Protective garment" , "Mac" , "Rain-resistant" , "Impervious to rain" .)