Area's excellent service stifling resistance (4)
I believe the answer is:
acre
'area's' is the definition.
(an acre is an area of land)
'excellent service stifling resistance' is the wordplay.
'excellent service' becomes 'ace' (excellent tennis serve).
'stifling' is an insertion indicator.
'resistance' becomes 'r' (electronics abbreviation).
'ace' enclosing 'r' is 'ACRE'.
(Other definitions for acre that I've seen before include "holy city" , "Square measure of land" , "Race (anag.)" , "Measure of land area" , "A state of W Brazil" .)