Slight shock initially to one making advances (7)
I believe the answer is:
slender
'slight' is the definition.
(synonyms)
'shock initially to one making advances' is the wordplay.
'initially' suggests taking the first letters.
'to one making advances' becomes 'lender' (I've seen this before).
The first letter of 'shock' is 's'.
's'+'lender'='SLENDER'
(Other definitions for slender that I've seen before include "Spare" , "Ann Page's suitor" , "associated with 7 [MEANS] suggests modest income" , "Barely sufficient (means)" , "short of a pound or two of flesh?" .)