Observe servant making escape (7)
I believe the answer is:
seepage
'escape' is the definition.
(thesaurus)
'observe servant' is the wordplay.
'observe' becomes 'see' (I've seen this before).
'servant' becomes 'page' (I've seen this before).
'see'+'page'='SEEPAGE'
'making' acts as a link.
(Other definitions for seepage that I've seen before include "Slow leakage" , "Discharge" , "problem with tank" , "Slow flow of fluid" , "Percolation" .)