Indicator of love concealed by playwright (7)
I believe the answer is:
pointer
'indicator' is the definition.
(I know that pointer is a type of indicator)
'love concealed by playwright' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'concealed by' is an insertion indicator.
'playwright' becomes 'pinter' (Harold Pinter).
'o' going inside 'pinter' is 'POINTER'.
'of' is the link.
(Other definitions for pointer that I've seen before include "Guide" , "Sign" , "Arrow" , "Smooth-haired game-dog" , "Gun dog" .)