Induce taut smile after surgery (9)
I believe the answer is:
stimulate
'induce' is the definition.
(I know that induce can be written as stimulate)
'taut smile after surgery' is the wordplay.
'after surgery' indicates anagramming the letters.
'taut'+'smile'='tautsmile'
'tautsmile' is an anagram of 'STIMULATE'.
(Other definitions for stimulate that I've seen before include "fire" , "Encourage" , "Excite the feelings of" , "Incite to action" , "Kindle?" .)