Weakling takes full advantage of surgical procedure (7)
I believe the answer is:
milksop
'weakling' is the definition.
(I've seen this before)
'takes full advantage of surgical procedure' is the wordplay.
'takes full advantage of' becomes 'milks' (as in milking an opportunity).
'surgical procedure' becomes 'op' (short for operation).
'milks'+'op'='MILKSOP'
(Other definitions for milksop that I've seen before include "Unmanly fellow" , "Feeble male" , "Namby-pamby" , "Weak or effeminate man" , "Chinless wonder" .)