Ask servant to find leak (7)
I believe the answer is:
seepage
'leak' is the definition.
(I've seen this in another clue)
'ask servant to find' is the wordplay.
I cannot really see how this works, but
'servant' could be 'page' (page can mean a boy servant) and 'page' is found in the answer.
'find' could be 'see' (synonyms) and 'see' is found within the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for seepage that I've seen before include "Slow flow of fluid" , "running out slowly" , "Oozing liquid" , "Discharge" , "liquid having soaked through" .)