In truth, poorly liver close to surgery (6)
I believe the answer is:
verily
'in truth' is the definition.
(I've seen this in another clue)
'poorly liver close to surgery' is the wordplay.
'poorly' indicates an anagram (a poor spelling).
'close to' indicates one should take the final letters (the 'close' to the word).
The final letter of 'surgery' is 'y'.
'liver' is an anagram of 'veril'.
'veril'+'y'='VERILY'
(Other definitions for verily that I've seen before include "It's livery, in truth" , "Truly (archaic)" .)